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Weight-Based Dose Calculator (mg/kg with maximum dose)

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 the dose against the product label or a pediatric formulary.

Weight (kg or lb)
Dose per kg (mg/kg)
Maximum dose (mg), optional
Concentration (mg/mL), optional

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Formula

Dose (mg) = dose (mg/kg) × weight (kg); if a maximum is given, dose = min(calculated, maximum). Volume (mL) = dose ÷ concentration (mg/mL).

Clinical pearls

Confirm which weight the drug label uses (actual, ideal or adjusted body weight); obese patients often should not be dosed on actual weight.
Check whether the mg/kg figure is per dose or per day before calculating.
Weigh children in kilograms: lb/kg confusion is a leading cause of pediatric dosing errors.

Examples

15 mg/kg for a 20 kg child, concentration 32 mg/mL weight based dose 10 mg/kg 80 kg max 600 mg dose for 44 lb child at 10 mg/kg

FAQ

How do you calculate a mg/kg dose?

Multiply the dose in mg/kg by the weight in kg. For 15 mg/kg in a 20 kg child, the dose is 300 mg. Cap it at the maximum dose if one applies.

How do I convert the dose to mL?

Divide the dose in mg by the concentration in mg/mL. 300 mg of a 160 mg/5 mL (32 mg/mL) suspension is 9.4 mL.

Evidence

Pan SD et al. Weight-based dosing in medication use: what should we know? Patient Prefer Adherence 2016;10:549–60.

Pharmacology & Dosing · Reviewed 2026-10-14 · Methodology