# AskCalc

> Every medical calculator, answered in plain English. 206 clinical calculators with exact, tested formulas and primary references. Each page states the formula, interpretation and evidence. Full text: https://askcalc.site/llms-full.txt · JSON: https://askcalc.site/api/calculators.json

## Cardiology

- [Age-Adjusted D-dimer Cutoff for Pulmonary Embolism](https://askcalc.site/calc/age-adjusted-d-dimer/): In patients older than 50 with non-high (or "PE unlikely") clinical probability, the D-dimer cutoff for excluding PE is age × 10 µg/L FEU (ng/mL) instead of the fixed 500 µg/L. A…
- [ASCVD 10-Year Risk (2013 Pooled Cohort Equations)](https://askcalc.site/calc/ascvd-pce/): The 2013 ACC/AHA Pooled Cohort Equations estimate 10-year risk of a first hard ASCVD event (CHD death, nonfatal MI, fatal or nonfatal stroke) for adults 40–79 without ASCVD. Risk…
- [ATRIA Bleeding Risk Score](https://askcalc.site/calc/atria-bleeding/): ATRIA predicts major hemorrhage on warfarin in atrial fibrillation (0–10 points): anemia 3, severe renal disease 3, age ≥75 2, prior hemorrhage 1, hypertension 1. Low risk 0–3…
- [Calculated LDL Cholesterol (Friedewald and Sampson/NIH)](https://askcalc.site/calc/ldl-calculated/): Friedewald LDL-C = total cholesterol − HDL − triglycerides/5 (mg/dL); invalid when triglycerides >400 mg/dL. The Sampson/NIH equation 2 is more accurate at high triglycerides (up…
- [Cardiac Output by the Fick Principle](https://askcalc.site/calc/cardiac-output-fick/): Fick cardiac output = O₂ consumption ÷ arteriovenous O₂ content difference, where O₂ content ≈ 1.34 × Hb × saturation (× 10 per litre). With estimated VO₂ of 125 mL/min/m²,…
- [CHA2DS2-VASc Score for Atrial Fibrillation Stroke Risk](https://askcalc.site/calc/cha2ds2-vasc/): CHA₂DS₂-VASc estimates annual stroke risk in non-valvular atrial fibrillation (0–9 points). Oral anticoagulation is recommended at ≥2 in men and ≥3 in women, and considered at 1…
- [CHADS-65 Algorithm (Canadian Cardiovascular Society) for AF Anticoagulation](https://askcalc.site/calc/chads-65/): The CCS "CHADS-65" algorithm recommends oral anticoagulation for AF if age ≥65 or any CHADS₂ risk factor (heart failure, hypertension, diabetes, prior stroke/TIA) is present;…
- [CHADS2 Score for Atrial Fibrillation Stroke Risk](https://askcalc.site/calc/chads2/): CHADS₂ estimates annual stroke risk in non-valvular atrial fibrillation (0–6 points): CHF, hypertension, age ≥75, diabetes 1 point each; prior stroke/TIA 2 points. It has largely…
- [Corrected QT Interval (QTc)](https://askcalc.site/calc/qtc/): Corrects the QT interval for heart rate. Bazett: QT/√RR (primary); Fridericia: QT/∛RR; Framingham: QT + 154 × (1 − RR); Hodges: QT + 1.75 × (HR − 60). QTc ≥450 ms (men) or ≥460…
- [Duke Treadmill Score](https://askcalc.site/calc/duke-treadmill/): Duke Treadmill Score = exercise time (min, Bruce) − 5 × maximal ST deviation (mm) − 4 × angina index. ≥+5 is low risk (~99% 4-year survival), −10 to +4 moderate (~95%), ≤−11 high…
- [EDACS (Emergency Department Assessment of Chest Pain Score)](https://askcalc.site/calc/edacs/): EDACS scores possible cardiac chest pain from age, sex, risk factors and pain features. EDACS < 16 with no new ischemia on ECG and negative 0 h and 2 h troponins (EDACS-ADP) is…
- [Framingham Risk Score (ATP III, 10-Year Hard CHD)](https://askcalc.site/calc/framingham-risk-score/): The ATP III Framingham equation estimates 10-year risk of hard coronary heart disease (MI or coronary death) in adults 30–79 without diabetes or CHD, from age, sex, total and HDL…
- [GRACE Score for In-Hospital Mortality in ACS](https://askcalc.site/calc/grace-acs/): The GRACE score (Granger 2003) estimates in-hospital mortality across the ACS spectrum from age, heart rate, SBP, creatinine, Killip class, cardiac arrest, ST deviation and…
- [H2FPEF Score for HFpEF Probability](https://askcalc.site/calc/h2fpef/): H₂FPEF (0–9) estimates the probability of heart failure with preserved ejection fraction in unexplained dyspnea: Heavy (BMI >30) 2, Hypertensive (≥2 drugs) 1, AF 3, Pulmonary…
- [HAS-BLED Score for Major Bleeding Risk in Atrial Fibrillation](https://askcalc.site/calc/has-bled/): HAS-BLED estimates 1-year major bleeding risk in atrial fibrillation patients on anticoagulation (0–9 points). A score ≥3 indicates high bleeding risk, which calls for closer…
- [HEART Score for Major Cardiac Events in Chest Pain](https://askcalc.site/calc/heart-score/): The HEART score (0–10) risk-stratifies emergency department chest pain for 6-week major adverse cardiac events: 0–3 low (MACE ~1.7%, candidate for early discharge), 4–6 moderate…
- [HEMORR2HAGES Bleeding Risk Score](https://askcalc.site/calc/hemorr2hages/): HEMORR₂HAGES estimates bleeding risk on warfarin in elderly AF patients (0–12): 2 points for prior bleed, 1 for each other factor. Bleeds per 100 patient-years: 1.9 (0), 2.5 (1),…
- [Hestia Criteria for Outpatient Pulmonary Embolism Treatment](https://askcalc.site/calc/hestia/): Hestia is an 11-item checklist for confirmed acute PE: if all answers are "no", the patient is eligible for outpatient anticoagulation (2.0% recurrent VTE, 1.0% mortality at 3…
- [Mean Arterial Pressure (MAP)](https://askcalc.site/calc/map/): Mean arterial pressure ≈ (SBP + 2 × DBP) ÷ 3, i.e. diastolic plus one-third of pulse pressure. Normal is about 70–100 mmHg; a MAP ≥65 mmHg is the usual initial target in septic…
- [Non-HDL Cholesterol](https://askcalc.site/calc/non-hdl-cholesterol/): Non-HDL cholesterol = total cholesterol − HDL cholesterol; it captures all atherogenic (apoB) lipoproteins and is valid non-fasting. ATP III targets are 30 mg/dL above the LDL…
- [ORBIT Bleeding Risk Score for Atrial Fibrillation](https://askcalc.site/calc/orbit-bleeding/): The ORBIT score (0–7) predicts major bleeding in AF patients on anticoagulation: 0–2 low (2.4 bleeds/100 patient-years), 3 medium (4.7), 4–7 high (8.1). Items: older age, reduced…
- [PERC Rule for Pulmonary Embolism](https://askcalc.site/calc/perc/): The PERC rule rules out PE without testing when pretest probability is low (<15%) and all 8 criteria are absent: age <50, HR <100, SpO₂ ≥95%, no hemoptysis, no estrogen use, no…
- [Pulmonary Embolism Severity Index (PESI)](https://askcalc.site/calc/pesi/): PESI predicts 30-day mortality in acute PE from 11 clinical variables. Class I (≤65) and II (66–85) are low risk (0–3.5% mortality) and may suit outpatient treatment; classes…
- [Revised Geneva Score for Pulmonary Embolism](https://askcalc.site/calc/geneva-revised/): The revised Geneva score (0–25) estimates clinical probability of PE from objective items only: 0–3 low (~8% PE), 4–10 intermediate (~28%), ≥11 high (~74%).
- [Sgarbossa Criteria (Original and Smith-Modified) for MI in LBBB](https://askcalc.site/calc/sgarbossa/): Sgarbossa criteria identify acute MI in left bundle branch block. Original (1996): concordant STE ≥1 mm (5), concordant STD ≥1 mm in V1–V3 (3), discordant STE ≥5 mm (2); ≥3…
- [Shock Index](https://askcalc.site/calc/shock-index/): Shock index is heart rate divided by systolic blood pressure. Normal is about 0.5–0.7; ≥1.0 suggests significant hypovolemia or shock and predicts transfusion need and mortality…
- [Simplified Pulmonary Embolism Severity Index (sPESI)](https://askcalc.site/calc/spesi/): sPESI scores 1 point each for age >80, cancer, chronic cardiopulmonary disease, HR ≥110, SBP <100 and SaO₂ <90%. A score of 0 is low risk (30-day mortality ~1.0%); ≥1 is high…
- [TIMI Risk Score for STEMI](https://askcalc.site/calc/timi-stemi/): The TIMI STEMI score (0–14) estimates 30-day mortality after ST-elevation MI, from 0.8% at 0 points to 35.9% at >8 points, using age, comorbidities, SBP, heart rate, Killip…
- [TIMI Risk Score for UA/NSTEMI](https://askcalc.site/calc/timi-ua-nstemi/): The TIMI score for unstable angina/NSTEMI (0–7) predicts 14-day all-cause death, new/recurrent MI or urgent revascularization, from 4.7% (score 0–1) to 40.9% (score 6–7). Scores…
- [Wells Score for Deep Vein Thrombosis](https://askcalc.site/calc/wells-dvt/): The modified Wells DVT score (−2 to 9) estimates pretest probability of lower-limb deep vein thrombosis: ≥2 "DVT likely" (ultrasound), <2 "DVT unlikely" (D-dimer first; if…
- [Wells Score for Pulmonary Embolism](https://askcalc.site/calc/wells-pe/): The Wells PE score (0–12.5) estimates pretest probability of pulmonary embolism. Two-tier: ≤4 "PE unlikely" (D-dimer first), >4 "PE likely" (CT pulmonary angiography).…
- [YEARS Algorithm for Pulmonary Embolism](https://askcalc.site/calc/years-algorithm/): YEARS rules out PE without imaging when there are no YEARS items (clinical signs of DVT, hemoptysis, PE most likely diagnosis) and D-dimer < 1000 ng/mL, or ≥1 item and D-dimer <…

## Nephrology & Electrolytes

- [Albumin-Corrected Delta Gap](https://askcalc.site/calc/albumin-corrected-delta-gap/): Albumin-corrected delta gap = albumin-corrected anion gap − 12, where corrected AG = Na − (Cl + HCO₃) + 2.5 × (4 − albumin g/dL). Compare it with the bicarbonate fall (24 −…
- [Albumin-Corrected Delta Ratio](https://askcalc.site/calc/albumin-corrected-delta-ratio/): Albumin-corrected delta ratio = (albumin-corrected AG − 12) ÷ (24 − HCO₃), with corrected AG = Na − (Cl + HCO₃) + 2.5 × (4 − albumin g/dL). <0.4 normal-gap acidosis, 0.4–0.8…
- [Bedside Schwartz eGFR (Pediatric)](https://askcalc.site/calc/schwartz-bedside/): The 2009 bedside Schwartz equation estimates GFR in children as 0.413 × height (cm) ÷ serum creatinine (mg/dL), in mL/min/1.73 m². Developed in children aged 1–16 with CKD;…
- [Bicarbonate Deficit](https://askcalc.site/calc/bicarbonate-deficit/): Bicarbonate deficit = 0.5 × weight (kg) × (target − measured HCO₃) mmol. Give about half over several hours and recheck; the apparent bicarbonate space rises as HCO₃ falls (0.4 +…
- [BUN:Creatinine Ratio (Urea:Creatinine)](https://askcalc.site/calc/bun-creatinine-ratio/): BUN:creatinine ratio (both mg/dL) is normally 10–20. A ratio >20 suggests prerenal azotaemia, upper GI bleeding, high protein intake or catabolism; <10 suggests intrinsic renal…
- [Calculated Serum Osmolality](https://askcalc.site/calc/serum-osmolality/): Calculated serum osmolality = 2 × Na + glucose/18 + BUN/2.8 (mg/dL), or in SI units 2 × Na + glucose + urea (mmol/L). Normal is about 275–295 mOsm/kg.
- [Corrected Calcium for Albumin](https://askcalc.site/calc/corrected-calcium/): Corrected calcium = measured calcium + 0.8 × (4.0 − albumin g/dL), or in SI units Ca + 0.02 × (40 − albumin g/L) mmol/L. Normal is about 8.5–10.5 mg/dL (2.10–2.60 mmol/L);…
- [Corrected Sodium in Hyperglycemia](https://askcalc.site/calc/corrected-sodium/): In hyperglycaemia, serum sodium falls as water shifts out of cells. Corrected Na = Na + 1.6 × (glucose − 100)/100 mg/dL (Katz) or + 2.4 per 100 mg/dL (Hillier, more accurate at…
- [Creatinine Clearance (Cockcroft-Gault)](https://askcalc.site/calc/cockcroft-gault/): Cockcroft-Gault estimates creatinine clearance as (140 − age) × weight ÷ (72 × serum creatinine), × 0.85 in women. It is still the reference for most renal drug-dosing labels;…
- [Delta Gap and Delta Ratio](https://askcalc.site/calc/delta-gap/): The delta ratio (ΔAG ÷ ΔHCO₃, with AG normal 12 and HCO₃ normal 24) detects mixed disorders in a high-anion-gap acidosis: <0.4 normal-gap acidosis, 0.4–0.8 combined high- and…
- [eGFR (CKD-EPI 2021 Creatinine–Cystatin C)](https://askcalc.site/calc/egfr-ckd-epi-2021-cys/): The race-free 2021 CKD-EPI creatinine–cystatin C equation combines both markers and is the most accurate routine eGFR; KDIGO recommends it to confirm CKD when creatinine-based…
- [eGFR (CKD-EPI 2021, race-free)](https://askcalc.site/calc/egfr-ckd-epi-2021/): Estimates glomerular filtration rate from serum creatinine, age and sex using the race-free 2021 CKD-EPI creatinine equation, the current recommended equation in North America.…
- [eGFR (MDRD Study equation)](https://askcalc.site/calc/egfr-mdrd/): The 4-variable IDMS-traceable MDRD equation, 175 × Scr^−1.154 × age^−0.203 (× 0.742 female), estimates GFR in mL/min/1.73 m². It has been superseded by CKD-EPI 2021 and…
- [Expected HCO3 in Respiratory Acidosis / Alkalosis](https://askcalc.site/calc/respiratory-compensation/): Expected HCO₃ for a primary respiratory disorder per 10 mmHg change in pCO₂ from 40: acute acidosis +1, chronic acidosis +3.5, acute alkalosis −2, chronic alkalosis −4 mmol/L. A…
- [Expected pCO2 in Metabolic Alkalosis](https://askcalc.site/calc/expected-pco2-metabolic-alkalosis/): In metabolic alkalosis pCO₂ rises about 0.7 mmHg per 1 mmol/L rise in HCO₃: expected pCO₂ ≈ 40 + 0.7 × (HCO₃ − 24) ± 5 mmHg. Compensation rarely pushes pCO₂ above about 55 mmHg.
- [Fractional Excretion of Sodium (FENa)](https://askcalc.site/calc/fena/): FENa = (urine Na × plasma creatinine) ÷ (plasma Na × urine creatinine) × 100. In oliguric AKI, FENa <1% suggests a prerenal cause and >2% suggests acute tubular necrosis;…
- [Fractional Excretion of Urea (FEUrea)](https://askcalc.site/calc/feurea/): FEUrea = (urine urea × plasma creatinine) ÷ (plasma urea × urine creatinine) × 100. FEUrea ≤35% suggests prerenal AKI and >50% suggests ATN; unlike FENa it remains useful after…
- [Free Water Deficit in Hypernatremia](https://askcalc.site/calc/free-water-deficit/): Free water deficit = total body water × (Na/140 − 1), with TBW = 0.6 × weight (men), 0.5 (women, older men), 0.45 (older women). Correct chronic hypernatraemia by no more than…
- [Kidney Failure Risk Equation (KFRE, 4-variable)](https://askcalc.site/calc/kfre/): The 4-variable KFRE (age, sex, eGFR, urine ACR) predicts 2- and 5-year risk of kidney failure requiring dialysis or transplant in CKD G3–G5. A 5-year risk ≥3–5% supports…
- [Serum Anion Gap (with Albumin Correction)](https://askcalc.site/calc/anion-gap/): Anion gap = Na − (Cl + HCO₃). A typical normal value is about 8–12 mmol/L (lab-dependent, often lower with modern analysers); higher suggests a high-anion-gap metabolic acidosis.…
- [Serum Osmolal Gap](https://askcalc.site/calc/osmolal-gap/): Osmolal gap = measured osmolality − (2 × Na + glucose/18 + BUN/2.8 [+ ethanol/3.7]). A gap above about 10 mOsm/kg suggests unmeasured osmoles such as methanol, ethylene glycol or…
- [Sodium Change per Litre of Infusate (Adrogué–Madias)](https://askcalc.site/calc/sodium-correction/): The Adrogué–Madias formula estimates the change in serum sodium after 1 L of a fluid: (infusate Na + K − serum Na) ÷ (total body water + 1). In chronic hyponatraemia limit…
- [Transtubular Potassium Gradient (TTKG)](https://askcalc.site/calc/ttkg/): TTKG = (urine K ÷ plasma K) × (plasma osm ÷ urine osm), an index of distal potassium secretion. In hyperkalaemia a TTKG <7 suggests inadequate aldosterone effect; in hypokalaemia…
- [Urine Anion Gap](https://askcalc.site/calc/urine-anion-gap/): Urine anion gap = urine Na + urine K − urine Cl, a surrogate for urinary ammonium in normal-anion-gap metabolic acidosis. A negative gap suggests GI bicarbonate loss (diarrhoea);…
- [Urine Osmolal Gap](https://askcalc.site/calc/urine-osmolal-gap/): Urine osmolal gap = measured urine osmolality − [2 × (urine Na + K) + urine urea nitrogen/2.8 + urine glucose/18]; urine NH₄⁺ ≈ gap ÷ 2. In a normal-anion-gap metabolic acidosis…
- [Urine Protein:Creatinine Ratio (Estimated 24-h Proteinuria)](https://askcalc.site/calc/upcr-proteinuria/): A spot urine protein:creatinine ratio in mg/mg (g/g) approximates daily protein excretion in g/day. <0.15 g/g (15 mg/mmol) is normal-to-mild, 0.15–0.5 moderately increased, >0.5…
- [Winters' Formula (Expected pCO2 in Metabolic Acidosis)](https://askcalc.site/calc/winters-formula/): Winters' formula predicts the pCO₂ in a compensated metabolic acidosis: expected pCO₂ = 1.5 × HCO₃ + 8 ± 2 mmHg. A measured pCO₂ above the range means a concurrent respiratory…

## Hepatology & GI

- [ABIC Score (Alcoholic Hepatitis)](https://askcalc.site/calc/abic/): ABIC = 0.1 × age + 0.08 × bilirubin (mg/dL) + 0.3 × creatinine (mg/dL) + 0.8 × INR. It stratifies 90-day survival in alcohol-associated hepatitis: <6.71 low risk (~100%),…
- [AIMS65 Score for Upper GI Bleeding](https://askcalc.site/calc/aims65/): AIMS65 predicts in-hospital mortality in upper GI bleeding with one point each for albumin <3.0 g/dL, INR >1.5, altered mental status, systolic BP ≤90 mmHg and age ≥65. Mortality…
- [ALBI Grade (Albumin-Bilirubin)](https://askcalc.site/calc/albi/): The ALBI score = 0.66 × log₁₀(bilirubin µmol/L) − 0.085 × albumin (g/L) grades liver function, particularly in hepatocellular carcinoma. Grade 1 ≤ −2.60, grade 2 > −2.60 to ≤…
- [Alvarado Score for Acute Appendicitis](https://askcalc.site/calc/alvarado/): The Alvarado (MANTRELS) score estimates the probability of acute appendicitis from 8 findings (0–10 points). Scores 1–4 make appendicitis unlikely, 5–6 are equivocal, 7–8…
- [APRI (AST to Platelet Ratio Index)](https://askcalc.site/calc/apri/): APRI = (AST ÷ AST upper limit of normal) ÷ platelets (10⁹/L) × 100. In hepatitis C, APRI ≤0.5 makes significant fibrosis unlikely, >1.5 makes it likely, and >2.0 suggests…
- [BISAP Score for Acute Pancreatitis Mortality](https://askcalc.site/calc/bisap/): BISAP (0–5) predicts in-hospital mortality in acute pancreatitis within the first 24 hours: one point each for BUN >25 mg/dL, impaired mental status, SIRS, age >60 and pleural…
- [Boston Bowel Preparation Scale (BBPS)](https://askcalc.site/calc/boston-bowel-prep/): The Boston Bowel Preparation Scale scores right, transverse and left colon cleanliness 0–3 each after washing and suctioning (total 0–9). Preparation is adequate for standard…
- [Child-Pugh Score for Cirrhosis](https://askcalc.site/calc/child-pugh/): Child-Pugh grades cirrhosis severity from bilirubin, albumin, INR, ascites and encephalopathy (5–15 points): class A 5–6 (well compensated), B 7–9 (significant functional…
- [Crohn's Disease Activity Index (CDAI)](https://askcalc.site/calc/cdai-crohns/): The CDAI (Best 1976) measures Crohn's disease activity from a 7-day diary plus exam, hematocrit and weight. CDAI <150 is remission, 150–219 mild, 220–450 moderate and >450…
- [CT Severity Index (Balthazar) for Acute Pancreatitis](https://askcalc.site/calc/ctsi-balthazar/): The CT Severity Index adds the Balthazar grade (A–E, 0–4 points) to the extent of pancreatic necrosis (none 0, ≤30% 2, 30–50% 4, >50% 6) for a 0–10 score: 0–3 mild, 4–6 moderate,…
- [FIB-4 Index for Liver Fibrosis](https://askcalc.site/calc/fib-4/): FIB-4 = (age × AST) ÷ (platelets × √ALT) estimates advanced liver fibrosis. In MASLD/NAFLD, <1.3 makes advanced fibrosis unlikely, 1.3–2.67 is indeterminate (needs elastography)…
- [Glasgow Alcoholic Hepatitis Score (GAHS)](https://askcalc.site/calc/gahs/): The Glasgow Alcoholic Hepatitis Score (5–12) uses age, white cell count, urea, PT ratio/INR and bilirubin to predict mortality in alcohol-associated hepatitis. A score ≥9…
- [Glasgow-Blatchford Bleeding Score (GBS)](https://askcalc.site/calc/glasgow-blatchford/): The Glasgow-Blatchford score (0–23) predicts need for transfusion, endoscopic therapy or surgery in upper GI bleeding using urea, hemoglobin, systolic BP, pulse and clinical…
- [Glasgow-Imrie Criteria for Acute Pancreatitis Severity](https://askcalc.site/calc/glasgow-imrie/): The modified Glasgow (Imrie) score counts 8 laboratory criteria within 48 hours of admission for acute pancreatitis (PaO₂ <60 mmHg, age >55, WBC >15, Ca <8 mg/dL, BUN >45 mg/dL,…
- [Harvey-Bradshaw Index (Crohn's Disease)](https://askcalc.site/calc/harvey-bradshaw/): The Harvey-Bradshaw Index scores Crohn's disease activity from well-being, abdominal pain, liquid stools per day, abdominal mass and complications. A score <5 indicates…
- [King's College Criteria for Liver Transplant in Acute Liver Failure](https://askcalc.site/calc/kings-college-criteria/): King's College Criteria identify acute liver failure patients unlikely to survive without transplant. Acetaminophen: arterial pH <7.30 after resuscitation, OR all of INR >6.5,…
- [Lille Model (Day 7, Alcoholic Hepatitis)](https://askcalc.site/calc/lille/): The Lille model assesses response to corticosteroids in severe alcohol-associated hepatitis using day-0 values and the change in bilirubin at day 7. A score ≥0.45 indicates…
- [Maddrey Discriminant Function (Alcoholic Hepatitis)](https://askcalc.site/calc/maddrey-df/): Maddrey's modified discriminant function = 4.6 × (patient PT − control PT) + bilirubin (mg/dL). A score ≥32 defines severe alcohol-associated hepatitis with high 1-month…
- [MELD 3.0 (Kim 2021, OPTN 2023)](https://askcalc.site/calc/meld-3/): MELD 3.0 adds female sex and albumin to MELD-Na with updated coefficients and a creatinine cap of 3.0 mg/dL; it has been used for US liver allocation since July 2023. Range 6–40;…
- [MELD Score (original UNOS MELD)](https://askcalc.site/calc/meld/): The original MELD score (UNOS version) predicts 3-month mortality in cirrhosis from bilirubin, INR and creatinine; range 6–40. Scores ≥15 generally warrant transplant referral;…
- [MELD-Na Score (UNOS/OPTN 2016)](https://askcalc.site/calc/meld-na/): MELD-Na adds serum sodium (bounded 125–137 mmol/L) to MELD and was used for US liver allocation from 2016 to 2023. The sodium correction applies only when MELD >11; range 6–40,…
- [Milan Criteria for Liver Transplantation in Hepatocellular Carcinoma](https://askcalc.site/calc/milan-criteria/): Milan criteria: a single HCC ≤5 cm, or up to 3 tumours each ≤3 cm, with no macrovascular invasion and no extrahepatic spread. Patients within Milan have about 75% 4-year survival…
- [Modified Marshall Score for Organ Failure (Acute Pancreatitis)](https://askcalc.site/calc/modified-marshall/): The modified Marshall score (revised Atlanta 2012) grades respiratory (PaO₂/FiO₂), renal (creatinine) and cardiovascular (systolic BP) function 0–4 each. A score ≥2 in any system…
- [NAFLD Fibrosis Score](https://askcalc.site/calc/nafld-fibrosis-score/): The NAFLD Fibrosis Score combines age, BMI, diabetes/IFG, AST/ALT ratio, platelets and albumin to estimate advanced fibrosis in fatty liver disease. Below −1.455 advanced…
- [Oakland Score for Lower GI Bleeding](https://askcalc.site/calc/oakland/): The Oakland score (0–35) predicts safe discharge in acute lower GI bleeding from age, sex, prior LGIB admission, rectal exam blood, heart rate, systolic BP and hemoglobin. A…
- [Partial Mayo Score (Ulcerative Colitis)](https://askcalc.site/calc/mayo-uc-partial/): The partial (non-invasive) Mayo score rates ulcerative colitis activity from stool frequency, rectal bleeding and physician global assessment (0–9) without endoscopy. Commonly:…
- [Ranson Criteria for Acute Pancreatitis](https://askcalc.site/calc/ranson/): Ranson's criteria score acute pancreatitis with 5 admission and 6 (non-gallstone) or 5 (gallstone) 48-hour criteria. A score ≥3 indicates severe pancreatitis; historical…
- [Rockall Score (Complete, Post-endoscopy)](https://askcalc.site/calc/rockall-full/): The complete Rockall score (0–11) adds endoscopic diagnosis and stigmata of recent haemorrhage to age, shock and comorbidity to predict rebleeding and death after upper GI…
- [Rockall Score (Pre-endoscopy / Clinical)](https://askcalc.site/calc/rockall-pre/): The pre-endoscopy (clinical) Rockall score (0–7) uses age, shock and comorbidity to estimate mortality in upper GI bleeding before endoscopy. A score of 0 identifies very low…
- [Serum-Ascites Albumin Gradient (SAAG)](https://askcalc.site/calc/saag/): SAAG = serum albumin − ascitic fluid albumin (same day). A SAAG ≥1.1 g/dL indicates portal hypertension (cirrhosis, heart failure, Budd-Chiari) with about 97% accuracy; <1.1 g/dL…
- [Stool Osmotic Gap](https://askcalc.site/calc/stool-osmotic-gap/): Stool osmotic gap = 290 − 2 × (stool Na + stool K). A gap >125 mOsm/kg suggests osmotic diarrhoea (e.g. magnesium, lactose, sorbitol); <50 mOsm/kg suggests secretory diarrhoea.
- [Truelove and Witts Criteria (Ulcerative Colitis Severity)](https://askcalc.site/calc/truelove-witts/): Truelove and Witts criteria classify ulcerative colitis flares. Acute severe UC = ≥6 bloody stools/day plus at least one sign of systemic toxicity: temperature >37.8 °C, pulse…

## Pulmonary & Critical Care

- [Alveolar–Arterial (A–a) O2 Gradient](https://askcalc.site/calc/a-a-gradient/): A–a gradient = PAO₂ − PaO₂, where PAO₂ = FiO₂ × (Patm − 47) − PaCO₂/0.8. On room air the normal gradient rises with age, roughly age/4 + 4 mmHg; a raised gradient points to V/Q…
- [APACHE II Score](https://askcalc.site/calc/apache-ii/): APACHE II grades ICU illness severity (0–71) from the worst values in the first 24 hours of 12 physiologic variables, plus age and chronic health points. Higher scores mean…
- [ARDSNet Tidal Volume (Predicted Body Weight)](https://askcalc.site/calc/ardsnet-tidal-volume/): Lung-protective ventilation targets a tidal volume of 6 mL/kg predicted body weight (range 4–8 mL/kg), with plateau pressure ≤30 cmH₂O. PBW (kg) = 50 + 0.91 × (height cm − 152.4)…
- [BODE Index for COPD Survival](https://askcalc.site/calc/bode/): The BODE index (0–10) predicts mortality in COPD from Body-mass index, airflow Obstruction (FEV₁ % predicted), Dyspnea (mMRC) and Exercise capacity (6-minute walk distance).…
- [CRB-65 Score for Pneumonia (no labs)](https://askcalc.site/calc/crb-65/): CRB-65 is CURB-65 without urea, for use where blood tests are unavailable: Confusion, Respiratory rate ≥30, SBP <90 or DBP ≤60, and age ≥65 (0–4 points). 0 is low risk (home…
- [CURB-65 Score for Pneumonia Severity](https://askcalc.site/calc/curb-65/): CURB-65 scores community-acquired pneumonia severity from Confusion, Urea >7 mmol/L (BUN >19 mg/dL), Respiratory rate ≥30, low Blood pressure (SBP <90 or DBP ≤60) and age ≥65…
- [Glasgow Coma Scale (GCS)](https://askcalc.site/calc/gcs/): The Glasgow Coma Scale sums eye opening (1–4), verbal response (1–5) and motor response (1–6) for a total of 3–15. Head injury severity: 13–15 mild, 9–12 moderate, ≤8 severe…
- [Light's Criteria for Pleural Effusion](https://askcalc.site/calc/lights-criteria/): Light's criteria classify a pleural effusion as an exudate if ANY of: pleural/serum protein ratio >0.5, pleural/serum LDH ratio >0.6, or pleural LDH >2/3 of the upper limit of…
- [NEWS2 (National Early Warning Score 2)](https://askcalc.site/calc/news2/): NEWS2 (Royal College of Physicians, 2017) aggregates respiratory rate, SpO₂ (Scale 1, or Scale 2 for hypercapnic patients with target 88–92%), supplemental oxygen, systolic BP,…
- [Oxygenation Index (OI)](https://askcalc.site/calc/oxygenation-index/): Oxygenation index = (mean airway pressure × FiO₂ % ) ÷ PaO₂. In ventilated children (PALICC 2015), OI 4–8 is mild, 8–16 moderate and ≥16 severe pediatric ARDS; in neonates, OI…
- [PaO2/FiO2 (P/F) Ratio with Berlin ARDS Severity](https://askcalc.site/calc/pf-ratio/): The PaO₂/FiO₂ ratio quantifies hypoxemia. Under the Berlin definition (with PEEP or CPAP ≥5 cmH₂O, acute onset, bilateral opacities and no cardiac explanation), ARDS is mild at…
- [Pneumonia Severity Index (PSI / PORT Score)](https://askcalc.site/calc/psi-port/): The Pneumonia Severity Index (Fine 1997) assigns community-acquired pneumonia patients to risk classes I–V by age, comorbidity, exam and lab findings. Classes I–II (≤70 points)…
- [qSOFA (Quick SOFA) Score for Sepsis](https://askcalc.site/calc/qsofa/): qSOFA flags adults with suspected infection at higher risk of death or prolonged ICU stay: respiratory rate ≥22, altered mentation (GCS <15) and systolic BP ≤100 mmHg, one point…
- [ROX Index for High-Flow Nasal Cannula](https://askcalc.site/calc/rox-index/): The ROX index = (SpO₂ / FiO₂) / respiratory rate predicts high-flow nasal cannula (HFNC) outcome in acute hypoxemic respiratory failure. ROX ≥4.88 at 2, 6 or 12 hours predicts…
- [SIRS Criteria (Systemic Inflammatory Response Syndrome)](https://askcalc.site/calc/sirs/): SIRS is present when ≥2 of 4 criteria are met: temperature >38 °C or <36 °C, heart rate >90, respiratory rate >20 or PaCO₂ <32 mmHg, and WBC >12 or <4 ×10⁹/L or >10% bands. SIRS…
- [SOFA Score (Sequential Organ Failure Assessment)](https://askcalc.site/calc/sofa/): SOFA scores dysfunction of six organ systems (respiratory, coagulation, liver, cardiovascular, CNS, renal) from 0 to 4 each, total 0–24. Under Sepsis-3, an acute rise of ≥2…
- [STOP-Bang Questionnaire for Obstructive Sleep Apnea](https://askcalc.site/calc/stop-bang/): STOP-Bang screens for obstructive sleep apnea with 8 yes/no items: Snoring, Tiredness, Observed apnea, high blood Pressure, BMI >35, Age >50, Neck circumference >40 cm, male…

## Infectious Disease

- [Centor Score (Modified / McIsaac) for Strep Pharyngitis](https://askcalc.site/calc/centor-mcisaac/): The McIsaac (modified Centor) score estimates the likelihood of group A streptococcal pharyngitis: 1 point each for fever >38 °C, absent cough, tender anterior cervical nodes and…
- [FeverPAIN Score for Streptococcal Pharyngitis](https://askcalc.site/calc/feverpain/): FeverPAIN scores 1 point each for Fever in the past 24 h, Purulence, Attending rapidly (≤3 days), severely Inflamed tonsils and No cough or coryza (0–5). 0–1: no antibiotic; 2–3:…
- [MASCC Risk Index for Febrile Neutropenia](https://askcalc.site/calc/mascc/): The MASCC risk index (0–26) identifies febrile neutropenic cancer patients at low risk of serious complications. A score ≥21 is low risk (candidates for oral/outpatient therapy…
- [Pitt Bacteremia Score](https://askcalc.site/calc/pitt-bacteremia/): The Pitt bacteremia score grades acute illness severity in bloodstream infection from temperature, hypotension, mechanical ventilation, cardiac arrest and mental status (0–14). A…

## Neurology

- [4AT Rapid Delirium Screen](https://askcalc.site/calc/four-at/): The 4AT (0–12) screens for delirium using Alertness, AMT4, Attention (months backwards) and Acute change/fluctuation. ≥4 suggests possible delirium ± cognitive impairment; 1–3…
- [ABCD² Score for TIA](https://askcalc.site/calc/abcd2/): ABCD² (0–7) estimates early stroke risk after TIA from Age, Blood pressure, Clinical features, Duration and Diabetes. 2-day stroke risk in the derivation cohorts: 0–3 low (1.0%),…
- [Hunt and Hess Scale for Subarachnoid Hemorrhage](https://askcalc.site/calc/hunt-hess/): The Hunt and Hess scale grades aneurysmal subarachnoid haemorrhage I–V from the clinical picture (I minimal headache → V deep coma). The original 1968 scale adds one grade for…
- [ICH Score (Intracerebral Hemorrhage)](https://askcalc.site/calc/ich-score/): The ICH score (0–6) predicts 30-day mortality after spontaneous intracerebral haemorrhage from GCS, hematoma volume ≥30 mL, intraventricular extension, infratentorial origin and…
- [NIH Stroke Scale (NIHSS)](https://askcalc.site/calc/nihss/): The NIHSS quantifies acute stroke deficit across 15 items (total 0–42). 0 = no measurable deficit, 1–4 minor, 5–15 moderate, 16–20 moderate-to-severe, 21–42 severe stroke.
- [Spetzler-Martin Grade for Brain AVM](https://askcalc.site/calc/spetzler-martin/): The Spetzler-Martin grade (I–V) estimates surgical risk for brain AVMs: nidus size (<3 cm 1, 3–6 cm 2, >6 cm 3) + eloquent location (1) + deep venous drainage (1). Spetzler-Ponce…
- [WFNS Grade for Subarachnoid Hemorrhage](https://askcalc.site/calc/wfns/): The WFNS scale grades aneurysmal subarachnoid haemorrhage I–V from the GCS and presence of a major focal motor deficit: I = GCS 15; II = GCS 13–14 without deficit; III = GCS…

## Emergency & Trauma

- [ABC Score for Massive Transfusion](https://askcalc.site/calc/abc-massive-transfusion/): The ABC (Assessment of Blood Consumption) score gives 1 point each for penetrating mechanism, ED SBP ≤90 mmHg, ED heart rate ≥120 and positive FAST. A score ≥2 predicts massive…
- [Canadian C-Spine Rule](https://askcalc.site/calc/canadian-c-spine/): For alert (GCS 15), stable adult trauma patients: image the cervical spine if any high-risk factor (age ≥65, dangerous mechanism, extremity paresthesias); otherwise, if a…
- [Canadian CT Head Rule](https://askcalc.site/calc/canadian-ct-head/): For adults with minor head injury (GCS 13–15 after witnessed loss of consciousness, amnesia or disorientation), CT is indicated if any of 5 high-risk (GCS <15 at 2 h, suspected…
- [Canadian Syncope Risk Score (CSRS)](https://askcalc.site/calc/canadian-syncope-risk-score/): The Canadian Syncope Risk Score (−3 to 11) estimates 30-day serious adverse events after ED syncope from 9 predictors. Categories: very low (−3 to −2), low (−1 to 0), medium…
- [NEXUS Criteria for C-Spine Imaging](https://askcalc.site/calc/nexus-c-spine/): After blunt trauma, cervical spine imaging is not required if all five NEXUS low-risk criteria are met: no posterior midline tenderness, no intoxication, normal alertness, no…
- [Ottawa Ankle Rules](https://askcalc.site/calc/ottawa-ankle/): Ankle X-ray is indicated if there is malleolar-zone pain plus bone tenderness at the posterior edge or tip of either malleolus, or inability to bear weight (4 steps) both…
- [Ottawa Knee Rule](https://askcalc.site/calc/ottawa-knee/): After acute knee injury, knee X-ray is indicated if any: age ≥55, isolated patellar tenderness, fibular head tenderness, inability to flex to 90°, or inability to bear weight (4…
- [Ottawa Subarachnoid Hemorrhage (SAH) Rule](https://askcalc.site/calc/ottawa-sah-rule/): For alert patients ≥15 years with new severe non-traumatic headache peaking within 1 hour, SAH needs investigation if any is present: age ≥40, neck pain or stiffness, witnessed…
- [Parkland Formula for Burn Resuscitation](https://askcalc.site/calc/parkland/): Parkland: 24-hour crystalloid (Ringer's lactate) = 4 mL × weight (kg) × %TBSA burned (partial + full thickness). Give half in the first 8 hours from the time of burn and the rest…
- [PECARN Pediatric Head Injury Rule (< 2 years)](https://askcalc.site/calc/pecarn-head-under2/): For children <2 years with minor head trauma (GCS 14–15): CT recommended if GCS 14/altered mental status or palpable skull fracture (ciTBI risk 4.4%); observation vs CT if…
- [PECARN Pediatric Head Injury Rule (≥ 2 years)](https://askcalc.site/calc/pecarn-head-2plus/): For children 2–17 years with minor head trauma (GCS 14–15): CT recommended if GCS 14/altered mental status or signs of basilar skull fracture (ciTBI risk 4.3%); observation vs CT…
- [Revised Trauma Score (RTS)](https://askcalc.site/calc/revised-trauma-score/): The Revised Trauma Score weights coded GCS, systolic BP and respiratory rate: RTS = 0.9368·GCSc + 0.7326·SBPc + 0.2908·RRc (0 to 7.84; lower is worse). The unweighted triage…
- [Rule of Nines (Adult Burn TBSA)](https://askcalc.site/calc/rule-of-nines/): Wallace rule of nines estimates adult burn size: head/neck 9%, each arm 9%, anterior trunk 18%, posterior trunk 18%, each leg 18%, perineum 1%. Count only partial- and…
- [San Francisco Syncope Rule](https://askcalc.site/calc/sf-syncope/): The San Francisco Syncope Rule (CHESS) flags ED syncope patients at risk of a serious outcome within 7 days if any is present: history of CHF, hematocrit <30%, abnormal ECG,…

## Pediatrics & Obstetrics

- [APGAR Score (Newborn Assessment)](https://askcalc.site/calc/apgar/): The APGAR score rates a newborn at 1 and 5 minutes on appearance, pulse, grimace, activity and respiration (0–2 each, total 0–10). A score of 7–10 is reassuring, 4–6 moderately…
- [Bishop Score (Cervical Ripeness for Induction)](https://askcalc.site/calc/bishop/): The Bishop score (0–13) rates cervical dilation, effacement, consistency, position and fetal station to predict successful induction of labour. A score >8 means vaginal delivery…
- [Brighton Paediatric Early Warning Score (PEWS)](https://askcalc.site/calc/pews-brighton/): The Brighton PEWS (0–13) scores behaviour, cardiovascular and respiratory status (0–3 each), plus 2 for quarter-hourly nebulisers and 2 for persistent post-operative vomiting.…
- [Estimated Conception Date from LMP](https://askcalc.site/calc/estimated-conception-date/): Estimated conception (ovulation) date = first day of the last menstrual period + 14 days, adjusted by (cycle length − 28) days. It is an estimate: fertilisation can occur up to…
- [Gestational Age from Due Date](https://askcalc.site/calc/gestational-age-from-edd/): Gestational age on a given date equals 280 days minus the days remaining until the estimated due date (EDD), expressed in completed weeks and days. Term is 37w0d–41w6d.
- [IVF Due Date (Embryo Transfer Date)](https://askcalc.site/calc/due-date-from-ivf/): For IVF pregnancies the due date is set from the embryo transfer date: EDD = transfer date + 266 days − embryo age, i.e. +261 days for a day-5 (blastocyst) transfer and +263 days…
- [Kocher Criteria for Septic Arthritis of the Hip (Children)](https://askcalc.site/calc/kocher-criteria/): Kocher criteria (non-weight-bearing, fever >38.5 °C, ESR >40 mm/h, WBC >12,000) distinguish septic arthritis of the hip from transient synovitis in children. Predicted…
- [Maintenance IV Fluids (Holliday-Segar 4-2-1 Rule)](https://askcalc.site/calc/holliday-segar/): Holliday-Segar maintenance fluid: 4 mL/kg/h for the first 10 kg, 2 mL/kg/h for the next 10 kg and 1 mL/kg/h for each kg above 20 (the 4-2-1 rule); daily equivalent 100/50/20…
- [PECARN Febrile Infant Rule (29–60 days)](https://askcalc.site/calc/pecarn-febrile-infant/): The PECARN rule classifies a well-appearing febrile infant (≥38.0 °C) as low risk for serious bacterial infection if the urinalysis is negative, ANC ≤ 4,090/µL and procalcitonin…
- [Pediatric Appendicitis Score (PAS, Samuel)](https://askcalc.site/calc/pediatric-appendicitis-score/): The Pediatric Appendicitis Score (Samuel 2002) rates suspected appendicitis in children aged 4–15 on a 10-point scale. A score ≥6 is consistent with appendicitis (Samuel); ≤3 is…
- [Pediatric Endotracheal Tube Size and Depth](https://askcalc.site/calc/ett-size-peds/): Pediatric endotracheal tube internal diameter for children ≥2 years: uncuffed = (age/4) + 4 mm, cuffed = (age/4) + 3.5 mm. Oral insertion depth at the lip ≈ 3 × uncuffed tube ID…
- [Pediatric Glasgow Coma Scale](https://askcalc.site/calc/pediatric-gcs/): The pediatric Glasgow Coma Scale (3–15) adapts verbal and motor responses for preverbal children: eye opening 1–4, verbal 1–5, motor 1–6. Severity: 13–15 mild, 9–12 moderate, ≤8…
- [Pediatric Weight Estimation by Age (APLS)](https://askcalc.site/calc/apls-weight/): APLS (6th edition) age-based weight estimates for resuscitation: 0–12 months (0.5 × age in months) + 4 kg; 1–5 years (2 × age) + 8 kg; 6–12 years (3 × age) + 7 kg. Use a measured…
- [PRAM (Pediatric Respiratory Assessment Measure) for Asthma](https://askcalc.site/calc/pram/): PRAM scores acute asthma severity in children (0–12) from suprasternal retraction, scalene contraction, air entry, wheezing and SpO₂. 0–3 mild, 4–7 moderate, 8–12 severe; a…
- [Pregnancy Due Date Calculator (Naegele's Rule from LMP)](https://askcalc.site/calc/due-date/): Naegele's rule estimates the due date as the first day of the last menstrual period (LMP) plus 280 days (40 weeks), adjusted by (cycle length − 28) days for non-28-day cycles. If…
- [Rochester Criteria (Low-Risk Febrile Infant ≤ 60 days)](https://askcalc.site/calc/rochester-criteria/): The Rochester criteria identify febrile infants ≤60 days at low risk for serious bacterial infection if well-appearing, previously healthy, without focal infection, with WBC 5–15…
- [Westley Croup Score](https://askcalc.site/calc/westley-croup/): The Westley croup score (0–17) grades croup severity from level of consciousness, cyanosis, stridor, air entry and retractions: ≤2 mild, 3–7 moderate, 8–11 severe, ≥12 impending…

## Hematology & Oncology

- [4Ts Score for Heparin-Induced Thrombocytopenia](https://askcalc.site/calc/four-ts-hit/): The 4Ts score estimates pretest probability of heparin-induced thrombocytopenia from Thrombocytopenia, Timing, Thrombosis and oTher causes (0–8). A score of 0–3 is low…
- [Absolute Neutrophil Count (ANC)](https://askcalc.site/calc/anc/): ANC = WBC × (% segmented neutrophils + % bands) ÷ 100. Neutropenia is ANC <1500/µL: mild 1000–1499, moderate 500–999, severe <500 (profound <100), which defines high infection…
- [ECOG Performance Status ↔ Karnofsky (KPS) Conversion](https://askcalc.site/calc/ecog-karnofsky/): Converts between ECOG (Zubrod/WHO) performance status 0–5 and the Karnofsky Performance Status 100–0 using the ECOG-ACRIN comparison: KPS 100–90 = ECOG 0, 80–70 = 1, 60–50 = 2,…
- [HScore for Reactive Hemophagocytic Lymphohistiocytosis (HLH)](https://askcalc.site/calc/hscore/): The HScore (Fardet 2014) estimates the probability of reactive hemophagocytic syndrome from 9 clinical, laboratory and marrow features (0–337 points). The best cutoff is 169…
- [International Prognostic Index (IPI) for Aggressive Lymphoma](https://askcalc.site/calc/ipi-dlbcl/): The IPI scores 5 adverse factors in aggressive non-Hodgkin lymphoma: age >60, stage III–IV, elevated LDH, ECOG ≥2 and >1 extranodal site. 0–1 is low risk (5-year OS 73%), 2…
- [Iron Deficit (Ganzoni Formula)](https://askcalc.site/calc/iron-deficit-ganzoni/): The Ganzoni formula estimates total body iron deficit for IV iron: weight (kg) × (target Hb − actual Hb, g/dL) × 2.4 + iron stores (500 mg if ≥35 kg). Default target Hb is 15…
- [ISTH Overt DIC Score](https://askcalc.site/calc/isth-dic/): The ISTH overt DIC score (0–8) combines platelet count, fibrin-related marker (D-dimer/FDP), PT prolongation and fibrinogen in a patient with an underlying disorder known to…
- [Khorana Score for Chemotherapy-Associated VTE](https://askcalc.site/calc/khorana/): The Khorana score predicts symptomatic VTE in ambulatory cancer patients starting chemotherapy (0–6). Score 0 is low risk (~0.8% at 2.5 months), 1–2 intermediate (~1.8%) and ≥3…
- [Mentzer Index (Thalassemia Trait vs Iron Deficiency)](https://askcalc.site/calc/mentzer-index/): Mentzer index = MCV (fL) ÷ RBC count (×10¹²/L). In microcytic anaemia, <13 suggests thalassaemia trait and >13 suggests iron deficiency.
- [Padua Prediction Score for VTE in Medical Inpatients](https://askcalc.site/calc/padua/): The Padua Prediction Score stratifies VTE risk in hospitalized medical patients (0–20). A score ≥4 is high risk (11% VTE without prophylaxis vs 0.3% if <4), and pharmacologic…
- [PLASMIC Score for TTP](https://askcalc.site/calc/plasmic/): The PLASMIC score (0–7) estimates the probability of severe ADAMTS13 deficiency (TTP) in thrombotic microangiopathy. 0–4 is low risk (0–4%), 5 intermediate (5–24%) and 6–7 high…
- [Reticulocyte Production Index (Corrected Reticulocyte Count)](https://askcalc.site/calc/reticulocyte-index/): The reticulocyte production index corrects the reticulocyte percentage for the degree of anemia (× Hct/45) and for prolonged circulation of premature reticulocytes (÷ maturation…
- [Revised International Prognostic Index (R-IPI) for DLBCL](https://askcalc.site/calc/r-ipi/): The R-IPI regroups the 5 IPI factors for DLBCL treated with R-CHOP: 0 factors = very good (4-year PFS 94%, OS 94%), 1–2 = good (PFS 80%, OS 79%), 3–5 = poor (PFS 53%, OS 55%).
- [Transferrin Saturation (TSAT)](https://askcalc.site/calc/transferrin-saturation/): Transferrin saturation = serum iron ÷ TIBC × 100. Normal is roughly 20–45%; <20% supports iron deficiency (absolute or functional), and a fasting value ≥45% warrants evaluation…

## Endocrine & Metabolic

- [2015 ACR/EULAR Gout Classification Criteria](https://askcalc.site/calc/gout-acr-eular-2015/): For patients with at least one episode of peripheral joint or bursa swelling, pain or tenderness, MSU crystals in synovial fluid or a tophus classify gout outright; otherwise a…
- [FINDRISC (Finnish Diabetes Risk Score)](https://askcalc.site/calc/findrisc/): FINDRISC (0–26) estimates 10-year risk of type 2 diabetes from age, BMI, waist, activity, diet, antihypertensives, prior high glucose and family history. <7 low (~1%), 7–11…
- [HbA1c to Estimated Average Glucose (ADAG)](https://askcalc.site/calc/a1c-eag/): Estimated average glucose (eAG) from HbA1c by the ADAG equation: eAG (mg/dL) = 28.7 × A1c − 46.7 (mmol/L = 1.59 × A1c − 2.59). An A1c of 7% corresponds to about 154 mg/dL (8.6…
- [HOMA-IR (Homeostatic Model Assessment of Insulin Resistance)](https://askcalc.site/calc/homa-ir/): HOMA-IR = fasting glucose (mg/dL) × fasting insulin (µU/mL) ÷ 405 (or glucose in mmol/L × insulin ÷ 22.5). Higher values mean more insulin resistance; there is no universal…
- [Inpatient Basal-Bolus Insulin Starting Dose (RABBIT 2)](https://askcalc.site/calc/insulin-starting-dose/): Weight-based inpatient basal-bolus insulin for non-critically ill adults with type 2 diabetes (RABBIT 2 trials): total daily dose 0.4 U/kg if glucose 140–200 mg/dL or 0.5 U/kg if…

## Psychiatry & Substance Use

- [Adult ADHD Self-Report Scale (ASRS v1.1) Screener, Part A](https://askcalc.site/calc/asrs-v1-1-screener/): The WHO ASRS v1.1 Screener asks 6 questions about ADHD symptoms over the past 6 months. Items 1–3 count as positive at "Sometimes" or more often and items 4–6 at "Often" or more…
- [AUDIT Alcohol Use Disorders Identification Test](https://askcalc.site/calc/audit/): The WHO AUDIT is a 10-item alcohol screen scored 0–40. Scores of 8 or more indicate hazardous or harmful drinking; WHO risk zones are 0–7 (low risk), 8–15 (simple advice), 16–19…
- [AUDIT-C Alcohol Use Screen](https://askcalc.site/calc/audit-c/): The AUDIT-C uses the first three AUDIT consumption questions (0–12 points) to screen for alcohol misuse. A score ≥4 in men or ≥3 in women is a positive screen; higher scores mean…
- [CAGE Questionnaire for Alcohol Use](https://askcalc.site/calc/cage/): CAGE asks four yes/no questions about Cutting down, Annoyance at criticism, Guilt and Eye-openers. Two or more "yes" answers are clinically significant for alcohol use disorder;…
- [CIWA-Ar Alcohol Withdrawal Scale](https://askcalc.site/calc/ciwa-ar/): The CIWA-Ar rates 10 alcohol withdrawal signs (nine scored 0–7, orientation 0–4), total 0–67. Scores below 10 usually need no medication; 10–15 is moderate withdrawal, and ≥16 is…
- [COWS Clinical Opiate Withdrawal Scale](https://askcalc.site/calc/cows/): The COWS rates 11 opioid withdrawal signs, total 0–48: 5–12 mild, 13–24 moderate, 25–36 moderately severe and >36 severe. It is commonly used to time buprenorphine induction,…
- [Edinburgh Postnatal Depression Scale (EPDS)](https://askcalc.site/calc/epds/): The EPDS is a 10-item self-report screen for perinatal depression scored 0–30 over the past 7 days. A score ≥10 suggests possible depression and ≥13 probable depression; any…
- [GAD-7 Generalized Anxiety Disorder Scale](https://askcalc.site/calc/gad-7/): The GAD-7 rates seven anxiety symptoms from 0 to 3 over the last 2 weeks, total 0–21. Scores of 5, 10 and 15 mark mild, moderate and severe anxiety; ≥10 identifies probable…
- [Hamilton Depression Rating Scale (HAM-D 17-item)](https://askcalc.site/calc/ham-d/): The 17-item Hamilton Depression Rating Scale is a clinician-rated measure of depression severity scored 0–52. Recommended severity bands (Zimmerman 2013) are 0–7 no depression,…
- [PHQ-9 Depression Severity (Patient Health Questionnaire-9)](https://askcalc.site/calc/phq-9/): The PHQ-9 scores the nine DSM depression criteria from 0 (not at all) to 3 (nearly every day) over the last 2 weeks, total 0–27. Scores of 5, 10, 15 and 20 mark mild, moderate,…
- [Primary Care PTSD Screen for DSM-5 (PC-PTSD-5)](https://askcalc.site/calc/pc-ptsd-5/): The PC-PTSD-5 is a 5-item yes/no PTSD screen for people who report a traumatic event, scored 0–5. The VA National Center for PTSD recommends a cut-point of 4 (best balance of…

## Pharmacology & Dosing

- [Corrected Phenytoin Level (Sheiner-Tozer / Winter-Tozer)](https://askcalc.site/calc/corrected-phenytoin/): Corrected phenytoin = measured total level ÷ (0.2 × albumin g/dL + 0.1); with CrCl <10 mL/min or ESRD, ÷ (0.1 × albumin + 0.1). The therapeutic total range is 10–20 mg/L; a free…
- [Corticosteroid Equivalent Dose Conversion](https://askcalc.site/calc/steroid-conversion/): Converts a systemic glucocorticoid dose to the equivalent dose of another using approximate anti-inflammatory equivalents: prednisone 5 mg = prednisolone 5 mg =…
- [Morphine Milligram Equivalents (MME) Calculator, CDC 2022](https://askcalc.site/calc/opioid-mme/): Total daily morphine milligram equivalents (MME) from the CDC 2022 conversion factors (e.g. oxycodone 1.5, hydromorphone 5, methadone 4.7, fentanyl patch 2.4 per mcg/h). Overdose…
- [Weight-Based Dose Calculator (mg/kg with maximum dose)](https://askcalc.site/calc/dose-weight-based/): Calculates a weight-based dose as mg/kg × weight (kg), capped at an optional maximum single dose, and converts it to a volume if a concentration (mg/mL) is given. Always check…

## Surgery & Perioperative

- [Apfel Score for Postoperative Nausea and Vomiting (PONV)](https://askcalc.site/calc/apfel/): The simplified Apfel score counts four PONV risk factors (female sex, non-smoker, history of PONV or motion sickness, postoperative opioids). 0, 1, 2, 3 and 4 factors predict…
- [Caprini Risk Assessment Model for VTE (2005)](https://askcalc.site/calc/caprini/): The 2005 Caprini risk assessment model sums weighted VTE risk factors (1, 2, 3 or 5 points each) in surgical patients. Scores 0–1 are low risk, 2 moderate, 3–4 high and ≥5…
- [Revised Cardiac Risk Index (RCRI, Lee Index)](https://askcalc.site/calc/rcri/): The RCRI counts 6 predictors of major cardiac complications after noncardiac surgery: high-risk surgery, ischemic heart disease, heart failure, cerebrovascular disease,…

## General & Anthropometrics

- [Adjusted Body Weight (Dosing Weight)](https://askcalc.site/calc/adjusted-body-weight/): Adjusted body weight = IBW + 0.4 × (actual weight − IBW), used for dosing drugs such as aminoglycosides and for Cockcroft-Gault in obesity, typically when actual weight exceeds…
- [Body Mass Index (BMI)](https://askcalc.site/calc/bmi/): BMI is weight in kilograms divided by height in metres squared. It classifies adults as underweight (<18.5), normal (18.5–24.9), overweight (25–29.9) or obese (≥30, classes I–III).
- [Body Surface Area (Mosteller)](https://askcalc.site/calc/bsa/): Body surface area by the Mosteller formula, √(height cm × weight kg ÷ 3600), used for chemotherapy dosing and indexing cardiac output. Average adult BSA is about 1.7–1.9 m².
- [Charlson Comorbidity Index (CCI)](https://askcalc.site/calc/charlson/): The age-adjusted Charlson Comorbidity Index weights 19 conditions (1–6 points each) plus 1 point per decade over 49, and estimates 10-year survival as 0.983^(e^(0.9 × CCI)). A…
- [Clinical Disease Activity Index (CDAI) for Rheumatoid Arthritis](https://askcalc.site/calc/cdai-ra/): The CDAI is the sum of 28-joint tender and swollen counts plus patient and evaluator global assessments (each 0–10), range 0–76, needing no lab test. Remission ≤2.8, low ≤10,…
- [DAS28-CRP (Disease Activity Score, 28 joints, CRP) for Rheumatoid Arthritis](https://askcalc.site/calc/das28-crp/): DAS28-CRP combines 28-joint tender and swollen counts, CRP (mg/L) and the patient global health rating (0–100 mm). The DAS28 thresholds (<2.6 remission, ≤3.2 low, ≤5.1 moderate,…
- [DAS28-ESR (Disease Activity Score, 28 joints, ESR) for Rheumatoid Arthritis](https://askcalc.site/calc/das28-esr/): DAS28-ESR combines 28-joint tender and swollen counts, ESR and the patient global health rating (0–100 mm) into a rheumatoid arthritis activity score. Thresholds: <2.6 remission,…
- [Harris-Benedict Equation (Revised, Roza & Shizgal 1984)](https://askcalc.site/calc/harris-benedict/): Revised Harris-Benedict (Roza & Shizgal 1984) estimates resting energy expenditure: men 88.362 + 13.397W + 4.799H − 5.677A; women 447.593 + 9.247W + 3.098H − 4.330A (W kg, H cm,…
- [Ideal Body Weight (Devine)](https://askcalc.site/calc/ibw/): Devine ideal body weight: men 50 kg + 2.3 kg per inch over 5 feet; women 45.5 kg + 2.3 kg per inch over 5 feet. Used for drug dosing (e.g. aminoglycosides, CrCl) and, as ARDSNet…
- [Lean Body Weight (Janmahasatian)](https://askcalc.site/calc/lean-body-weight/): Janmahasatian lean body weight (fat-free mass): men 9270 × W ÷ (6680 + 216 × BMI); women 9270 × W ÷ (8780 + 244 × BMI). Valid across extremes of body size and used for scaling…
- [Mifflin-St Jeor Equation (Resting Energy Expenditure)](https://askcalc.site/calc/mifflin-st-jeor/): Mifflin-St Jeor estimates resting energy expenditure: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) + 5 for men, or − 161 for women. It is the most accurate predictive…
- [Number Needed to Treat (NNT) / Harm (NNH)](https://askcalc.site/calc/nnt/): From the control (CER) and experimental (EER) event rates: absolute risk reduction ARR = CER − EER, relative risk reduction RRR = ARR ÷ CER, and NNT = 1 ÷ ARR (rounded up). If…
- [Pack-Years Smoking History](https://askcalc.site/calc/pack-years/): Pack-years = packs smoked per day × years smoked (1 pack = 20 cigarettes). USPSTF 2021 recommends annual low-dose CT lung cancer screening for adults 50–80 with ≥20 pack-years…
- [Post-Test Probability from Likelihood Ratio (Bayes)](https://askcalc.site/calc/likelihood-ratio-posttest/): Converts a pre-test probability to a post-test probability with a likelihood ratio: post-test odds = pre-test odds × LR. Enter an LR directly, or sensitivity, specificity and…
- [Sensitivity, Specificity, PPV, NPV from a 2×2 Table](https://askcalc.site/calc/sens-spec/): From a 2×2 table of true positives (TP), false positives (FP), false negatives (FN) and true negatives (TN): sensitivity = TP/(TP+FN), specificity = TN/(TN+FP), PPV = TP/(TP+FP),…
- [Simplified Disease Activity Index (SDAI) for Rheumatoid Arthritis](https://askcalc.site/calc/sdai-ra/): The SDAI is the sum of 28-joint tender and swollen counts, patient and evaluator global assessments (0–10) and CRP in mg/dL. Remission ≤3.3, low ≤11, moderate ≤26, high >26.
- [Target Weight for a Target BMI](https://askcalc.site/calc/target-weight/): Target weight = target BMI × height (m)². For example, a BMI of 25 at 1.75 m is 76.6 kg. Add current weight to see how many kilograms must be lost or gained.
- [Temperature Conversion (°C ↔ °F)](https://askcalc.site/calc/temperature-conversion/): Converts body temperature between Celsius and Fahrenheit: °C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32. Normal is about 37 °C (98.6 °F); fever is ≥38 °C (100.4 °F).
- [Total Body Water (Watson Formula)](https://askcalc.site/calc/total-body-water-watson/): The Watson formula estimates total body water from sex, age, height and weight (men: 2.447 − 0.09516·age + 0.1074·height + 0.3362·weight; women: −2.097 + 0.1069·height +…