How this calculator works
The weight bands are cumulative: allow 100 mL/kg/day for the first 10 kg, 50 for the next 10 kg and 20 for each kilogram above 20. The hourly 4-2-1 shortcut is shown separately because it does not equal daily volume divided by 24. These are starting estimates for clinical assessment. They do not cover neonatal fluid transitions, resuscitation, deficits, ongoing losses or fluid restriction. Fluid composition and monitoring require an individual plan. No automatic bolus is inferred from maintenance needs. The result is an estimate for information only and is not medical advice.
Formula
Daily mL = 100 min(W,10) + 50 min(max(W-10,0),10) + 20 max(W-20,0). Hourly 4-2-1 mL/h = 4 min(W,10) + 2 min(max(W-10,0),10) + max(W-20,0).
Worked example
For 25 kg: 1000 + 500 + 100 = 1600 mL/day, or 66.67 mL/h; 4-2-1 gives 65 mL/h. For 8 kg: 800 mL/day, or 33.33 mL/h; 4-2-1 gives 32 mL/h.
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Frequently asked questions
Why are the hourly answers different?
The shortcuts round each weight band: 100/24 is about 4.17, 50/24 about 2.08 and 20/24 about 0.83. The rules are related estimates with different arithmetic.
Does this calculate a resuscitation bolus?
No. Boluses depend on the reason for treatment and the patient's condition. A maintenance calculation cannot choose one.
Can the estimate be used unchanged in all children?
No. Neonates and children with cardiac, renal, endocrine or other acute illness may need different volumes and close monitoring.