Free Maintenance Fluids Calculator

Weight

Holliday-Segar Method (daily)

First 10 kg: 100 ml/kg/24h
Next 10 kg (11-20): 50 ml/kg/24h
Above 20 kg: 20 ml/kg/24h

4-2-1 Rule (hourly)

First 10 kg: 4 ml/kg/h
Next 10 kg (11-20): 2 ml/kg/h
Above 20 kg: 1 ml/kg/h

Results

Enter a child's weight to calculate maintenance fluids.

Understanding the Pediatric Maintenance Fluids Calculator

The Pediatric Maintenance Fluids Calculator is a free online tool that applies the Holliday-Segar method and its derivative, the 4-2-1 rule, to compute daily and hourly intravenous fluid needs for children. It also serves as a pediatric fluid bolus calculator, providing the recommended volume for rapid infusion in emergency scenarios. This IV fluids calculator for children is designed to help clinicians quickly derive accurate maintenance fluid rates without manual computation.

Important Usage Guidelines

Before using the calculator, note the following limitations:

It is not intended for neonates under 14 days of age or children weighing less than 3 kg, as the underlying formula overestimates fluid requirements in these populations.
For obese pediatric patients, the ideal body weight should be used in place of actual weight to avoid overhydration.

How to Use the Calculator

Simply enter the child's weight. The tool instantly generates three key values:

Daily maintenance fluids – total volume required over 24 hours.
Fluids flow rate – the infusion rate in mL per hour for IV administration.
Pediatric fluid bolus – the amount to be given in acute hypovolemia.

The Holliday-Segar Method and the 4-2-1 Rule

Developed by pediatricians Malcolm Holliday and William Segar, these remain the most widely used formulas for pediatric maintenance fluid calculation. They rely on the principle that fluid needs correlate with metabolic rate, which is proportional to body weight. The 4-2-1 rule is simply the hourly equivalent of the daily Holliday-Segar method.

The standard rates are as follows:

Weight range	Holliday-Segar (daily)	4-2-1 rule (hourly)
3–10 kg	100 mL/kg	4 mL/kg
11–20 kg	50 mL/kg	2 mL/kg
>20 kg	20 mL/kg	1 mL/kg

To obtain the total daily volume, combine the contributions from each weight segment:

First 10 kg: $100 \,\text{mL/kg} \times 10\,\text{kg} = 1000\,\text{mL}$
Second 10 kg: $50 \,\text{mL/kg} \times 10\,\text{kg} = 500\,\text{mL}$
Every additional kilogram above 20 kg: $20 \,\text{mL/kg}$ per kg

The same logic applies for the hourly rate using the 4-2-1 rule values.

Practical Example

Consider a child weighing 14 kg:

Daily maintenance: $(100 \times 10) + (50 \times 4) = 1000 + 200 = 1200\,\text{mL/24h}$
Hourly flow rate: $(4 \times 10) + (2 \times 4) = 40 + 8 = 48\,\text{mL/h}$

The calculator performs these calculations automatically, eliminating the need for manual steps.

Pediatric Fluid Bolus

A fluid bolus is a rapid intravenous infusion administered in life‑threatening situations such as hypovolemic shock to quickly expand intravascular volume. The recommended bolus volume for children is computed as:

\text{Bolus volume (mL)} = \text{weight (kg)} \times 20

The upper limit is 1000 mL (1 L). Because shock demands immediate action, this volume should be infused as quickly as possible.

Unit Conversion

The built‑in weight converter allows seamless switching between metric and imperial units, ensuring accessibility for all users.

Disclaimer

This calculator is for informational and educational purposes only. It does not replace clinical judgment or professional medical advice. Always consult a qualified healthcare provider before initiating or adjusting any fluid therapy.

FAQ

1. How is the daily maintenance fluid volume calculated for a child using the Holliday-Segar method?

The daily volume is computed by summing the requirements for each weight segment: for the first 10 kg, 100 mL/kg; for the next 10 kg (11–20 kg), 50 mL/kg; and for any weight above 20 kg, 20 mL/kg per additional kilogram. For example, a 14 kg child needs 1000 mL (first 10 kg) + 200 mL (next 4 kg) = 1200 mL/24h.

2. What is the 4-2-1 rule and how does it relate to the Holliday-Segar method?

The 4-2-1 rule is the hourly version of the Holliday-Segar method. It uses 4 mL/kg/h for the first 10 kg, 2 mL/kg/h for the next 10 kg, and 1 mL/kg/h for each kg above 20 kg. The hourly rates directly correspond to the daily rates divided by 24.

3. When should a pediatric fluid bolus be administered, and how is the volume determined?

A pediatric fluid bolus is given rapidly in hypovolemic shock to quickly restore intravascular volume. The volume is calculated as weight (kg) × 20 mL, with a maximum of 1000 mL. The infusion should be delivered as fast as possible in emergency settings.

4. Can this calculator be used for newborns under 14 days or very low‑weight infants?

No. The Holliday‑Segar method overestimates fluid needs for neonates younger than 14 days and for children weighing less than 3 kg. The calculator is not recommended for these populations.

5. Should actual body weight always be used for maintenance fluid calculations in children?

For obese children, it is advisable to use the ideal body weight rather than actual weight to avoid fluid overload. The calculator allows you to adjust the input accordingly.

How to Use

Enter your child's weight in kilograms, pounds, or stones.
The calculator automatically computes the daily and hourly maintenance fluids needs based on the Holliday-Segar method and 4-2-1 rule.
Review the recommended daily maintenance fluids, IV flow rate, and fluid bolus amount for your pediatric patient.