Maintenance Fluids (Holliday-Segar) Calculator

Maintenance Fluids (Holliday-Segar) Calculator for Pediatrics. The result is a rate, not a score: it is the continuous baseline to run before adding deficit or replacement fluids. The most important modern caveat concerns tonicity, not volume. Because Holliday-Segar was historically paired with hypotonic fluids (e.g., 0.2%-0.45% saline), that combination is now recognized as a major driver of iatrogenic hospital-acquired hyponatremia in acutely ill children, who often have non-osmotic ADH release. Current practice keeps the Holliday-Segar volume but uses isotonic maintenance fluid. In many acutely ill or postoperative children, clinicians also deliberately restrict to roughly two-thirds of the calculated volume to further reduce hyponatremia risk. Always check a baseline and follow-up serum sodium.

How this calculator works

The Holliday-Segar method estimates 24-hour maintenance water needs from body weight alone, using the empiric observation that water use parallels caloric expenditure (roughly 100 mL per 100 kcal metabolized). The "4-2-1" rule gives the hourly rate: 4 mL/kg/hr for the first 10 kg, plus 2 mL/kg/hr for the second 10 kg, plus 1 mL/kg/hr for every kilogram above 20 kg. The equivalent daily version is 100 mL/kg for 0-10 kg, 50 mL/kg for 10-20 kg, and 20 mL/kg for each kg beyond 20 kg. A 20 kg child needs 60 mL/hr; a 30 kg child needs 70 mL/hr.

When to use this calculator

Use for a euvolemic child who cannot take adequate oral intake and needs a starting IV rate for ongoing physiologic losses (urine, stool, insensible). It does NOT replace an existing deficit or ongoing abnormal losses (vomiting, diarrhea, third-spacing, drains, polyuria), which are calculated and added separately. It should not be applied unmodified to neonates under about 2-4 weeks (different insensible losses and renal handling), or to children with heart failure, renal failure, oliguria, SIADH, or cerebral salt wasting, where free-water and electrolyte handling are deranged and full maintenance volumes may cause harm.

Inputs used

  • Weight
  • Clinical context
  • Electrolyte and fluid restrictions when applicable

Clinical interpretation

The result is a rate, not a score: it is the continuous baseline to run before adding deficit or replacement fluids. The most important modern caveat concerns tonicity, not volume. Because Holliday-Segar was historically paired with hypotonic fluids (e.g., 0.2%-0.45% saline), that combination is now recognized as a major driver of iatrogenic hospital-acquired hyponatremia in acutely ill children, who often have non-osmotic ADH release. Current practice keeps the Holliday-Segar volume but uses isotonic maintenance fluid. In many acutely ill or postoperative children, clinicians also deliberately restrict to roughly two-thirds of the calculated volume to further reduce hyponatremia risk. Always check a baseline and follow-up serum sodium.

Worked example

A 26 kg child: first 10 kg gives 40 mL/hr (4x10), next 10 kg gives 20 mL/hr (2x10), remaining 6 kg gives 6 mL/hr (1x6), totaling 66 mL/hr, or about 1,584 mL/day. Paired with an isotonic fluid such as 0.9% saline or lactated Ringer's (typically plus 5% dextrose and added potassium once urine output is established), this sets the baseline continuous rate before any deficit or abnormal-loss replacement is added.

Limitations and safety notes

The formula assumes normal metabolic rate and normal renal, cardiac, and neuroendocrine function; fever (add ~10-12% per degree Celsius above 38), hypermetabolic states, and burns increase needs, while hypothermia, mechanical ventilation with humidified gas, oliguria, and SIADH decrease them. It systematically overestimates needs in the acutely ill child with elevated ADH, and its historical pairing with hypotonic fluid caused symptomatic hyponatremia, seizures, and deaths. It is not validated for neonates in the first weeks of life, and in obese children weight-based calculation overestimates requirements because adipose tissue is metabolically inactive.

Frequently asked questions

Why is 0.9% saline now preferred over 0.45% saline for maintenance?

Acutely ill and postoperative children frequently have non-osmotic ADH secretion, so free water from hypotonic fluid is retained rather than excreted, dropping serum sodium. The 2018 AAP guideline recommends isotonic fluid with appropriate KCl and dextrose for most children 28 days to 18 years to prevent hospital-acquired hyponatremia.

Does the 4-2-1 rule change in fever or other high-loss states?

The base calculation stays the same, but you add for abnormal losses. A common adjustment adds roughly 10-12% to maintenance for each degree Celsius of sustained temperature above 38. Ongoing GI or drain losses are measured and replaced separately, milliliter-for-milliliter, rather than folded into the maintenance rate.

Should I ever run less than the full calculated volume?

Yes. In children at high risk of SIADH (postoperative, CNS disease, pneumonia, bronchiolitis), many clinicians restrict to about two-thirds of calculated maintenance and monitor sodium closely, because full volume plus retained free water can precipitate hyponatremia.

Is this method valid for newborns?

No. Term and preterm neonates in the first weeks of life have higher insensible losses, transitional renal handling, and different day-by-day fluid requirements, so they follow neonatal fluid protocols rather than Holliday-Segar.

How does the daily calculation relate to the hourly 4-2-1 rule?

They are the same physiology expressed differently: 100/50/20 mL/kg/day for successive weight bands equals 4/2/1 mL/kg/hr. The daily version caps around 2,400 mL/day (100 kg equivalent) in older practice, and adult-sized adolescents are often given a fixed adult maintenance rate instead.

References

  • Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957. PMID: 13431307.
  • Feld LG, Neuspiel DR, Foster BA, et al. Clinical Practice Guideline: Maintenance Intravenous Fluids in Children. Pediatrics. 2018. PMID: 30478247.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: June 11, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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