Holliday-Segar Fluid Maintenance Calculator (4-2-1 Rule)
The Holliday-Segar 4-2-1 rule is the standard method for calculating maintenance fluid requirements in children, accounting for daily insensible losses, urinary output, and growth needs.
About
The Holliday-Segar method, published in 1957, estimates maintenance fluid requirements based on caloric expenditure. Using the 4-2-1 rule: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the second 10 kg, and 1 mL/kg/hr for each additional kg. This translates to approximately 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the second 10 kg, and 20 mL/kg/day thereafter. The method also guides deficit replacement in dehydrated children, where the deficit is calculated as weight × dehydration% × 1000 mL, with half replaced over the first 8 hours and half over the next 16 hours, in addition to ongoing maintenance needs.
Formula
Hourly rate = 4 mL/kg (first 10kg) + 2 mL/kg (second 10kg) + 1 mL/kg (remaining). Daily volume = Hourly × 24.
The 4-2-1 rule calculates hourly maintenance IV fluid rate. For the first 10 kg multiply by 4, for kg 11-20 multiply by 2, and for remaining kg multiply by 1. Sum all components for total hourly rate. Multiply by 24 for daily volume.
Score Interpretation
Proper fluid management is critical in pediatric care. Dehydration from gastroenteritis is a leading cause of emergency visits in children. The Holliday-Segar method provides standardized maintenance fluid rates. However, recent evidence suggests caution with hypotonic fluids in hospitalized children due to risk of hyponatremia. Isotonic maintenance fluids (such as D5 1/2NS with 20 mEq/L KCl) are increasingly recommended by AAP and NICE guidelines.
Fluid Rate — 0+
Holliday-Segar maintenance calculation.
Management: Use calculated rate for IV fluid therapy.
Reference Ranges
| Population | Normal Range | Notes |
|---|---|---|
| Children >28 days to adults | 4-2-1 rule dependent on weight | Recent AAP guidelines recommend isotonic fluids for maintenance in hospitalized children |
Dr. Khaled Hassan
Dr. Khaled is a cardiology consultant with experience in acute cardiac care.
View medical review board & editorial policy →Example Calculation
A 15 kg child: hourly rate = (10×4) + (5×2) = 40 + 10 = 50 mL/hr. Daily = 50 × 24 = 1200 mL/day. If 8% dehydrated: deficit = 15 × 0.08 × 1000 = 1200 mL. Replace 600 mL over 8h + maintenance, then 600 mL over 16h + maintenance.
Related Conditions
Related Medications
Common Mistakes
Using hypotonic fluids (D5W, D5 1/4NS) for maintenance
Use isotonic fluids (D5 1/2NS or D5 NS with KCl) to prevent hyponatremia in hospitalized children.
Frequently Asked Questions
What is the 4-2-1 rule?
When should I include deficit replacement?
References
- Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832. PubMed
- NICE Guideline NG189: Intravenous fluid therapy in children and young people in hospital (2023).