What is the Holliday-Segar method?

The Holliday-Segar method is the most widely used formula for estimating daily fluid maintenance requirements in children. It assigns 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 additional 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/hour for the first 10 kg, 2 mL/kg/hour for the next 10 kg, and 1 mL/kg/hour for weight above 20 kg. Both approaches yield the same results.

Is this calculator suitable for adults?

The Holliday-Segar formula was developed for pediatric patients. For adults, most clinicians use a fixed rate (e.g., 25–30 mL/kg/day) or disease-specific protocols. This calculator can still compute values for adult weights, but clinical judgment is always required.

Does this account for ongoing losses or dehydration?

No. This calculator provides maintenance fluids only — the baseline volume needed to replace insensible and obligate losses in a normally hydrated patient. Deficit replacement, ongoing losses (e.g., diarrhea, drainage), and disease-specific adjustments must be calculated and added separately.

What fluid type should be used for maintenance?

Fluid type selection (e.g., 0.9% NaCl, 0.45% NaCl + dextrose, lactated Ringer's) depends on the clinical scenario, electrolytes, and institutional protocol. This calculator outputs rate only, not fluid composition.

Is the result the same whether I use kg or lbs?

Yes. When you select pounds, the calculator converts to kilograms first (1 lb = 0.453592 kg) before applying the formula, so the result is equivalent.

Fluid Maintenance Calculator

Name: Fluid Maintenance Calculator
Availability: InStock
Author: Nham Vu

Enter a patient's weight to instantly calculate daily IV fluid maintenance requirements using the Holliday-Segar (4-2-1) method.

Patient Weight

Unit

Weight (kg)

Quick presets (kg)

Enter a weight above and click Calculate to see the fluid maintenance rate.

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