How it's calculated
The Holliday-Segar method estimates maintenance fluid requirement from body weight using tiered rates — a smaller amount per kg for the first 10 kg, less for the next 10 kg, and even less for each kg above that, reflecting that metabolic (and therefore fluid) requirement doesn't scale linearly with weight.
Worked examples
| Weight | Daily volume | Hourly rate |
|---|---|---|
| 5 kg | 500 mL/24h | 20 mL/hr |
| 10 kg | 1000 mL/24h | 40 mL/hr |
| 15 kg | 1250 mL/24h | 50 mL/hr |
| 20 kg | 1500 mL/24h | 60 mL/hr |
| 30 kg | 1700 mL/24h | 70 mL/hr |
Clinical use
- This calculates maintenance fluid only — pre-existing deficits (e.g. dehydration from vomiting/diarrhoea) and ongoing abnormal losses (drains, fever, burns) must be assessed and replaced separately, on top of this maintenance rate.
- Use with caution, and often at a reduced rate, in cardiac failure, significant renal impairment, SIADH, raised intracranial pressure, or other fluid-restricted states.
- Isotonic fluids (rather than hypotonic maintenance fluids) are now generally preferred for most hospitalised children, per updated paediatric fluid-safety guidance — confirm current local protocol for fluid choice and composition.
Frequently asked questions
What is the Holliday-Segar method?
A weight-based method (Holliday & Segar, 1957) for estimating a child's daily maintenance fluid requirement, using tiered mL/kg rates that decrease as weight increases — reflecting that larger children have proportionally lower metabolic and fluid needs per kg than smaller ones.
Why do the daily and hourly figures not divide exactly evenly?
The 100/50/20 mL/kg/day tiers and the 4/2/1 mL/kg/hr tiers are two separate, independently-taught companion mnemonics for the same underlying concept — 4 mL/kg/hr × 24 hours = 96 mL/kg/day, not exactly 100. This small rounding difference is well-recognised and doesn't affect clinical use; both are used interchangeably in practice.
Does this include fluid deficit replacement?
No — this is maintenance fluid only. A child who is dehydrated, has ongoing losses (vomiting, diarrhoea, drain output), or has increased insensible losses (fever, burns, phototherapy) needs additional fluid calculated and added on top of the maintenance volume shown here.
What type of fluid should be used for maintenance?
Isotonic fluids (e.g. balanced crystalloids) are now generally recommended over hypotonic solutions for most hospitalised children, following safety concerns about hyponatraemia with hypotonic maintenance fluids — always confirm current local paediatric fluid-prescribing protocol.
References
- Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832.
- National Institute for Health and Care Excellence (NICE). Intravenous fluid therapy in children and young people in hospital. NG29.