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Maintenance Fluids (4-2-1 Rule) Calculator

Hourly maintenance IV fluid rate from weight.

Compute the hourly maintenance IV fluid rate using the Holliday–Segar 4-2-1 rule: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for every kg thereafter.

Priya Venkatesan By Priya Venkatesan
Reviewed by Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

kg

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Up to 10 kg: 4 mL/kg/hr. 10–20 kg: +2 mL/kg/hr. >20 kg: +1 mL/kg/hr per additional kg.

In depth

Compute the hourly maintenance IV fluid rate using the Holliday–Segar 4-2-1 rule: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for every kg thereafter.