What is the Holliday-Segar method?

The Holliday-Segar method is the standard formula for estimating daily maintenance fluid requirements in children. It uses three weight brackets: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg (10–20 kg), and 20 mL/kg/day for each kilogram above 20 kg.

What is the "4-2-1 rule"?

The 4-2-1 rule is the hourly equivalent of the Holliday-Segar formula: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr above 20 kg. Both approaches give the same result when multiplied or divided by 24.

Does this apply to neonates under 72 hours old?

No. Neonates in the first 72 hours of life have different fluid requirements due to insensible losses and renal immaturity. Consult neonatal-specific guidelines and a neonatologist for those patients.

Is this tool a substitute for clinical judgment?

No. This calculator provides a baseline estimate. Actual fluid orders must account for the patient's clinical status, ongoing losses, electrolyte levels, and the prescribing clinician's judgment.

What is the maximum weight the calculator handles?

The calculator accepts weights up to 100 kg. The uncapped Holliday–Segar formula shown by this tool gives 3,100 mL/day (about 129.2 mL/hr) at 100 kg. Actual orders may use a lower adult cap based on clinical status and prescriber judgment.

Can I use pounds instead of kilograms?

Yes. Toggle the unit selector to lb and enter the weight in pounds. The calculator converts to kilograms internally before applying the formula.

Pediatric Maintenance Fluids Calculator

Enter a child's weight to instantly calculate IV maintenance fluid rate (mL/hr) and 24-hour volume using the Holliday-Segar formula.

Patient Weight

Weight (kg)

Enter weight between 0.5 and 100 kg (or equivalent in lb).

Holliday-Segar Formula

First 10 kg100 mL/kg/day
Next 10 kg (10–20 kg)50 mL/kg/day
Each kg above 20 kg20 mL/kg/day

Enter a weight and press Calculate

Hourly Rate

—

mL/hr

Daily Volume

—

mL/day

Weight used —

Bracket Breakdown

Bracket	kg Applied	mL/day
Total	—	—

For reference only. Clinical decisions must involve a qualified healthcare provider. Does not apply to neonates <72 hours old or patients with special fluid restrictions.

Summary

This tool computes the standard IV maintenance fluid requirements for pediatric patients using the Holliday-Segar method: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, and 20 mL/kg/day for each kilogram above 20 kg. Enter the patient's weight in kilograms or pounds to get the 24-hour volume and hourly infusion rate instantly.

How it works

Enter the child's weight in kilograms or pounds.
The calculator applies the Holliday-Segar formula to the entered weight.
The 24-hour maintenance volume is computed across the three weight brackets.
The hourly rate (mL/hr) is derived by dividing the daily volume by 24.
Results update in real time as you type.
A breakdown table shows how each weight bracket contributes to the total.

Use cases

Quickly determine IV fluid orders for pediatric inpatients.
Verify nursing fluid calculations at the bedside.
Educational reference for medical students learning fluid management.
Double-check orders for neonates and infants in the NICU or ED.
Calculate fluid deficits and replacement alongside maintenance needs.
Use during pediatric ACLS or emergency scenarios.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu