- Enter the child's weight (default kg; switch to lb if needed). For obese children, use ideal body weight to avoid over-prescribing fluid.
- The daily volume and hourly rate update automatically using the Holliday-Segar tiers (100 / 50 / 20 mL/kg per day = 4 / 2 / 1 mL/kg/hr).
- The result assumes a euvolemic, afebrile patient with normal insensible losses. Adjust for fever (≈ +12% per 1 °C above 38), tachypnea, phototherapy, burns, or ongoing GI / urinary losses; restrict in oliguric AKI, SIADH, heart failure, post-op (transient ADH), and severe renal or cardiac disease.
- Use an isotonic fluid (0.9% NaCl or a balanced crystalloid such as Ringer's lactate / Plasma-Lyte) for maintenance in most hospitalized children — AAP 2018 — to prevent hospital-acquired hyponatremia from hypotonic fluids. Add dextrose (typically D5) for caloric support.
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When to Use
Use the Holliday-Segar method to estimate the routine maintenance IV fluid requirement for a pediatric (or small adult) patient who is unable to take adequate oral intake — perioperative, hospitalized for an acute illness, or NPO for a procedure. It replaces the predictable, ongoing losses (urine + insensible) of a euvolemic, afebrile child. It is not a resuscitation calculation and is not intended to correct an existing deficit on its own.
Appropriate population
Children and adolescents (and small adults) who are euvolemic, afebrile, and clinically stable but cannot meet their normal water and electrolyte needs by mouth. Especially helpful for NPO patients, perioperative orders, and inpatient maintenance lines.
When NOT to use it alone
Holliday-Segar is not a resuscitation rule and does not account for an existing deficit or ongoing pathological losses. Do not use it as the sole prescription in shock or significant dehydration (use bolus resuscitation first), in oliguric AKI / advanced CKD, SIADH, heart failure, or post-operative states with brisk ADH release (restrict instead). For burns, DKA, and severe gastroenteritis, follow disease-specific protocols. In obese children, switch to ideal body weight to avoid over-prescribing.
Pearls & Pitfalls
4-2-1 is just the hourly form of 100-50-20
The daily tiers (100 / 50 / 20 mL/kg/day) and the hourly tiers (4 / 2 / 1 mL/kg/hr) are the same rule — 100 mL ÷ 24 h ≈ 4 mL/hr, 50 ÷ 24 ≈ 2, 20 ÷ 24 ≈ 1 (rounded for bedside use). Memorize one; the other follows. Quick checks: 8 kg → 800 mL/day, 32 mL/hr · 15 kg → 1250 mL/day, 50 mL/hr · 25 kg → 1600 mL/day, 65 mL/hr · 70 kg → 2500 mL/day, 110 mL/hr.
Use isotonic fluids (AAP 2018)
The 2018 AAP Clinical Practice Guideline recommends an isotonic fluid (0.9% NaCl or a balanced crystalloid such as Ringer's lactate / Plasma-Lyte) — with appropriate dextrose and potassium — for maintenance in most hospitalized children aged 28 days to 18 years. Hypotonic maintenance fluids (e.g., 0.2% or 0.45% NaCl) carry a clinically meaningful risk of hospital-acquired hyponatremia, particularly in the setting of non-osmotic ADH release (pain, nausea, post-op, pneumonia, CNS disease). Add D5 for caloric support; tailor potassium to chemistry.
When to add, when to restrict
Add volume for fever (≈ +12% per 1 °C above 38), tachypnea, phototherapy, radiant warmers, burns, third-spacing, and ongoing GI / urinary / surgical-drain losses (replace measured losses mL-for-mL). Restrict in oliguric AKI, advanced CKD, SIADH, heart failure, severe liver disease, the early post-op period (transient ADH), and any condition with reduced free-water clearance — start at roughly two-thirds maintenance and titrate to weight, urine output, and serum sodium.
Pitfalls
(1) Not for resuscitation — boluses (typically 10–20 mL/kg isotonic crystalloid) go in before the maintenance rate is set. (2) Don't use actual body weight in obese children — switch to ideal body weight, otherwise the prescription will substantially overestimate need. (3) In a typical adult, the strict Holliday-Segar formula keeps climbing as weight rises; routine maintenance is rarely run above ~2400 mL/day (~100 mL/hr) in an otherwise stable adult — show the formula value, but cap the practical order. (4) Always re-evaluate at 24 h with weights, urine output, and serum sodium — never set maintenance fluids "and forget."
Why Use It
Holliday and Segar's 1957 paper anchored maintenance fluid prescribing in caloric expenditure, observing that water requirements track energy use in a predictable, weight-banded way: roughly 100 mL per 100 kcal metabolized, with the first 10 kg of body weight burning ~100 kcal/kg/day, the next 10 kg ~50 kcal/kg/day, and each additional kg ~20 kcal/kg/day. The hourly "4-2-1" shorthand is the same rule rounded for bedside arithmetic. For the past six decades it has remained the universal starting point for pediatric maintenance fluid orders precisely because it is simple, weight-based, and reproducible. The modern refinement — driven by repeated reports of fatal hospital-acquired hyponatremia — is that the volume from Holliday-Segar is correct in most stable patients, but the composition should be isotonic, not hypotonic (AAP 2018, Moritz & Ayus 2015). Use this calculator for the volume; pair it with an isotonic crystalloid + appropriate dextrose / potassium for the prescription.
Holliday-Segar Maintenance Fluids (4-2-1)
Enter the patient's weight to get the 24-hour maintenance volume and the corresponding hourly rate, plus the per-tier breakdown. Use ideal body weight in obese children, and adjust up or down for fever, ongoing losses, or restrictive states (see Pearls).
⚕ Holliday MA, Segar WE. Pediatrics. 1957;19(5 Pt 1):823–832. Holliday-Segar estimates routine, maintenance water needs in a euvolemic, afebrile patient. It is not a resuscitation rule and does not correct an existing deficit or ongoing losses. Per AAP 2018, use an isotonic fluid (0.9% NaCl or balanced crystalloid) with appropriate dextrose and potassium for most hospitalized children. Adjust up for fever / losses / phototherapy / burns; restrict in oliguric AKI, SIADH, heart failure, post-op (transient ADH), and severe renal or cardiac disease. For licensed clinicians; not a substitute for individualized assessment.
Next Steps
Translate the Holliday-Segar volume into a concrete, safe prescription.
- Pick the fluid (AAP 2018). Default to an isotonic crystalloid for maintenance — 0.9% NaCl or a balanced solution (Ringer's lactate, Plasma-Lyte). Add D5 for caloric support. Tailor potassium (often KCl 20 mEq/L once urine output is established and chemistry confirms it is safe).
- Adjust the volume for the clinical situation. Add for fever (≈ +12% per 1 °C above 38), tachypnea, phototherapy, radiant warmers, burns, or measured ongoing losses; restrict to roughly two-thirds maintenance in oliguric AKI, SIADH, heart failure, or the early post-op period.
- Treat any deficit or shock first. Boluses (typically 10–20 mL/kg isotonic crystalloid, reassessed each time) precede the maintenance order. Holliday-Segar replaces ongoing losses — it does not correct an existing deficit.
- Re-evaluate at least daily. Trend weight, urine output, fluid balance, and serum sodium / potassium; titrate volume and composition accordingly. For a stable adult, cap the routine maintenance at ~2400 mL/day (~100 mL/hr) — anything higher should be deliberate (loss replacement, polyuria, burns).
- Pair this with the adult maintenance fluids calculator for older patients and the pediatric eGFR (Schwartz) when assessing kidney function before fluid orders.
Evidence & References
Formula — Daily Volume
| Weight tier | Daily water (mL/kg/day) |
|---|---|
| First 10 kg | 100 mL/kg/day |
| Next 10 kg (10–20 kg) | 50 mL/kg/day |
| Each kg above 20 kg | 20 mL/kg/day |
Formula — Hourly Rate (the 4-2-1 Rule)
| Weight tier | Hourly rate (mL/kg/hr) |
|---|---|
| First 10 kg | 4 mL/kg/hr |
| Next 10 kg (10–20 kg) | 2 mL/kg/hr |
| Each kg above 20 kg | 1 mL/kg/hr |
Worked Examples
| Weight | Daily volume | Hourly rate |
|---|---|---|
| 8 kg | 8 × 100 = 800 mL/day | 8 × 4 = 32 mL/hr |
| 15 kg | 1000 + 5 × 50 = 1250 mL/day | 40 + 5 × 2 = 50 mL/hr |
| 25 kg | 1000 + 500 + 5 × 20 = 1600 mL/day | 40 + 20 + 5 × 1 = 65 mL/hr |
| 70 kg | 1000 + 500 + 50 × 20 = 2500 mL/day | 40 + 20 + 50 × 1 = 110 mL/hr |
For a typical adult, routine maintenance is rarely run above ~2400 mL/day (~100 mL/hr); the formula value is shown, but the prescribed order should reflect the clinical situation (volume status, kidney function, cardiac function).
Fluid Composition (AAP 2018)
| Setting | Recommendation |
|---|---|
| Maintenance in hospitalized children (28 d – 18 y) | Isotonic crystalloid (0.9% NaCl or balanced) with appropriate dextrose and potassium |
| Hypotonic fluids (0.2% / 0.45% NaCl) as maintenance | Discouraged — associated with hospital-acquired hyponatremia |
| Restrictive states (oliguric AKI, SIADH, HF, post-op) | Start at ~⅔ maintenance; titrate to weight, urine output, and serum sodium |
References
- Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5 Pt 1):823–832.
- Feld LG, Neuspiel DR, Foster BA, et al. Clinical Practice Guideline: Maintenance Intravenous Fluids in Children. Pediatrics. 2018;142(6):e20183083. doi:10.1542/peds.2018-3083.
- Moritz ML, Ayus JC. Maintenance Intravenous Fluids in Acutely Ill Patients. N Engl J Med. 2015;373(14):1350–1360. doi:10.1056/NEJMra1412877.
