Maintenance Fluids Calculator for Children — Holliday-Segar
The Holliday-Segar method calculates maintenance intravenous fluid requirements for children from body weight alone — splitting the calculation into three weight bands (0–10 kg, 10–20 kg, >20 kg) to reflect how metabolic rate changes with size.
kg
Holliday-Segar IV maintenance rate
- 1
First 10 kg (100 mL/kg/day)
100 × 10 = 1,000 - 2
Next 10 kg (50 mL/kg/day)
50 × 5 = 250 - 3
Daily total
1,000 + 250 = 1,250 - 4
Hourly rate = daily ÷ 24
1,250 ÷ 24 = 52.1Divide the daily volume by 24 to get the continuous IV infusion rate in mL/hr.
How does this calculator work?
Maintenance fluid need (mL/day) = 100 × first 10 kg + 50 × next 10 kg + 20 × remaining kg (Holliday-Segar, 1957). Divide by 24 for the hourly rate. For a 15 kg child: 1 250 mL/day = ~52 mL/hr. This is a clinical starting point — adjust for fever, losses and comorbidities with clinician oversight.
Formula
How this is calculated
Holliday and Segar (1957) observed that caloric expenditure — and therefore water loss — follows a predictable stepped relationship with body weight in children. Larger children have proportionally lower metabolic rates per kilogram, so the per-kg fluid allowance decreases in steps: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg (11–20 kg), and 20 mL/kg/day for every kilogram beyond 20 kg. These same factors expressed per hour give the convenient "4-2-1 rule" (4/2/1 mL/kg/hr).
For a 15 kg child: (10 × 100) + (5 × 50) = 1 000 + 250 = 1 250 mL/day = 52 mL/hr.
This formula estimates maintenance requirements only under normal conditions — it does not account for fever, diarrhoea, surgical losses, cardiac or renal disease, neonates (who have different requirements), or hypotonic/hypertonic states. Always confirm with local protocols and a qualified clinician before prescribing fluids.
Frequently asked questions
The 4-2-1 rule is the hourly version of Holliday-Segar: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for each kg above 20 kg. Both give the same result — just expressed per hour rather than per day.
No. Neonates (especially premature infants) have very different fluid requirements influenced by insensible losses through immature skin, gestational age and postnatal day. Neonatal fluid prescribing uses separate protocols and should always involve a specialist.
Common reasons to adjust include fever (+10–15% per °C above 38 °C), vomiting and diarrhoea (add replacement losses), mechanical ventilation (reduce by ~30% for humidified circuits), and significant burns or surgical drains. Always use clinical judgement.
Also known as
TG we-Calculate Editorial Team. (2026). Maintenance Fluids Calculator for Children — Holliday-Segar [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/maintenance-fluids-children-calculator
TG we-Calculate Editorial Team. "Maintenance Fluids Calculator for Children — Holliday-Segar." TG we-Calculate. 2026. https://we-calculate.com/calculator/maintenance-fluids-children-calculator.
TG we-Calculate Editorial Team, "Maintenance Fluids Calculator for Children — Holliday-Segar," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/maintenance-fluids-children-calculator
@misc{wecalculate_maintenance_fluids_children_calculator, title = {Maintenance Fluids Calculator for Children — Holliday-Segar}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/maintenance-fluids-children-calculator}}, year = {2026}, note = {TG we-Calculate} }
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