Interpretation
| Result | Meaning |
|---|---|
| 0–10 kg | 4 mL/kg/h (100 mL/kg/day) |
| 10–20 kg | 40 mL/h + 2 mL/kg/h above 10 kg (1000 + 50 mL/kg/day above 10 kg) |
| > 20 kg | 60 mL/h + 1 mL/kg/h above 20 kg (1500 + 20 mL/kg/day above 20 kg) |
Formula
mL/h = 4 × (first 10 kg) + 2 × (next 10 kg) + 1 × (each kg > 20) · mL/day = 100 × (first 10 kg) + 50 × (next 10 kg) + 20 × (each kg > 20)
Clinical pearls
- AAP 2018 guideline: use isotonic fluid (e.g. 0.9% saline or balanced solution with dextrose) for maintenance in children 28 days–18 years to reduce hyponatremia.
- Many centres cap adult-size patients at about 100–120 mL/h (2.4–3 L/day); restrict in SIADH risk, heart failure or renal failure.
- Not for neonates < 28 days or for replacing deficits and ongoing losses.
Examples
maintenance fluids 25 kg4-2-1 rule for an 8 kg infantholliday segar 70 kgwhat IV rate for a 44 lb child
FAQ
What is the 4-2-1 rule?
Hourly maintenance fluid is 4 mL/kg for the first 10 kg, 2 mL/kg for the next 10 kg and 1 mL/kg for every kg above 20 kg.
Why do 4-2-1 and 100/50/20 give slightly different numbers?
4-2-1 is a rounded hourly version of the daily rule (100 mL/kg/day ÷ 24 ≈ 4.2 mL/kg/h), so it runs about 2–4% lower.