Holliday-Segar maintenance fluids

Independent clinical validation: pending

Two independent clinical validators will be named here once review is complete.

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How it is calculated

Daily maintenance volume uses the 100-50-20 rule: 100 mL/kg for the first 10 kg, plus 50 mL/kg for each kg between 10 and 20 kg, plus 20 mL/kg for each kg above 20 kg. The hourly rate uses the derivative 4-2-1 rule: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for each kg between 10 and 20 kg, and 1 mL/kg/hr for each kg above 20 kg. Both rules describe the same water need, but the hourly coefficients are the daily coefficients divided by 24 and rounded (100÷24≈4.17, 50÷24≈2.08, 20÷24≈0.83), so the hourly rate multiplied by 24 does not exactly equal the daily volume.

Limitations and notes

Estimate of baseline (basal-state) maintenance water only — not a prescription or order. It EXCLUDES any pre-existing fluid deficit (dehydration) and ongoing/abnormal losses (fever, vomiting, diarrhea, drains, third-spacing), which are computed and added separately. There are no interpretation bands: the output is a target volume, not a risk tier. Derived for children in a basal metabolic state and not intended for neonates younger than ~2 weeks; accuracy is reduced in fever, hypothermia, hyperthyroidism, and status epilepticus. The two outputs disagree slightly by design: the 4-2-1 hourly rule uses rounded coefficients, so hourly × 24 ≠ daily volume (the hourly rule slightly underestimates in the first two brackets and slightly overestimates above 20 kg). The 1957 method paired this volume with hypotonic, dextrose-containing fluid; contemporary evidence links routine hypotonic maintenance fluids to iatrogenic hyponatremia and current guidance generally favors isotonic maintenance fluids — the volume rule stands, the 1957 composition is superseded (an authoritative isotonic-fluid guideline citation is [NEEDS SOURCE]). Many centers cap total maintenance volume for large patients (commonly stated near ~2000–2400 mL/day) rather than extrapolating the >20 kg bracket indefinitely; any such cap is an institutional policy overlay and the specific numeric value is [NEEDS SOURCE] — the 1957 paper specifies no ceiling.

Accepted input ranges

Body weight — 0.5–150 kg

References

Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823–832.PMID 13431307 DOI 10.1542/peds.19.5.823
University of Iowa Head and Neck Protocols — Pediatric Fluid Management. Secondary confirmation of the 4-2-1 hourly rule and the 35 kg → 75 mL/hr worked example.Source

Version and changelog

v1.0.0 · Fluids and resuscitation

2026-07-25 v1.0.0 — Initial release: 100-50-20 daily volume and 4-2-1 hourly rate from body weight; no bands.

Important

For use by qualified health professionals as an informational and educational aid. It supports clinical judgment and does not replace it. Verify every result independently before making a clinical decision. This is not a medical device.