What it is
The Holliday-Segar method estimates a child’s daily maintenance water requirement from body weight. It assumes water needs parallel energy expenditure, giving a weight-banded estimate that remains the default starting point for prescribing maintenance IV fluids in pediatrics.
The formula
Daily volume (100/50/20 rule):
- First 10 kg: 100 mL/kg/day
- Next 10 kg (11–20 kg): 50 mL/kg/day
- Each kg above 20 kg: 20 mL/kg/day
Hourly rate (4/2/1 rule) — the same estimate divided by 24:
- First 10 kg: 4 mL/kg/hr
- Next 10 kg: 2 mL/kg/hr
- Each kg above 20 kg: 1 mL/kg/hr
The daily total typically caps around 2,400 mL/day (≈100 mL/hr) in larger children, reflecting the energy-expenditure plateau.
When to use it
Use it to set a baseline maintenance rate in a euvolemic child who cannot meet needs enterally. It does not include deficit (dehydration) or ongoing losses (diarrhea, drains, fever, third-spacing) — add those separately.
Worked example
A 26 kg child:
- 10 kg × 100 = 1,000 mL
- 10 kg × 50 = 500 mL
- 6 kg × 20 = 120 mL
- Total = 1,620 mL/day
Hourly (4/2/1): 40 + 20 + 6 = 66 mL/hr (≈1,584 mL/day; the small difference is rounding between the daily and hourly rules).
Pitfalls and caveats
- Tonicity matters more than volume. Major guidance (NICE NG29, AAP 2018) now recommends isotonic maintenance fluid (e.g., 0.9% saline or balanced crystalloid, usually with 5% dextrose and appropriate potassium) to reduce iatrogenic hyponatremia. Hypotonic fluids are a recognized cause of fatal hyponatremic encephalopathy.
- Holliday-Segar overestimates needs in conditions with reduced free-water clearance or non-osmotic ADH release: post-op, meningitis/CNS disease, pneumonia, SIADH, bronchiolitis. Consider restricting to 50–70% of calculated maintenance and monitor sodium.
- It underestimates in fever (add ~12%/°C above normal), burns, and high insensible losses.
- Reassess clinically and biochemically — it is a starting estimate, not a fixed prescription. Check electrolytes before and during therapy.
- For neonates and very low birth weight infants, use age/day-specific neonatal fluid regimens instead.
Run it now: Maintenance Fluid Calculator
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.