Holliday–Segar Daily Maintenance Fluid Calculator

Overview

Calculates estimated daily maintenance fluid using the Holliday–Segar 100/50/20 rule.

Clinical Significance

Maintenance estimates must be adjusted for illness, enteral intake, renal function, electrolytes and ongoing losses.

When to Use

• Use when the calculation is relevant to the clinical question.
• Confirm that the population and units match the validated method.
• Use current and reliable measurements.

How It Is Calculated

• 100 mL/kg for first 10 kg, 50 mL/kg for next 10 kg, then 20 mL/kg.

Interpretation

• Maintenance estimates must be adjusted for illness, enteral intake, renal function, electrolytes and ongoing losses.
• Interpret alongside the full clinical picture and current guidance.

Worked Example

Enter the required measurements in the stated units. MedicalC then applies: 100 mL/kg for first 10 kg, 50 mL/kg for next 10 kg, then 20 mL/kg.

Patient Considerations

• Consider age, body size, pregnancy, organ function and treatment effects where relevant.
• Repeat the calculation when inputs or clinical status materially change.

Limitations

• Accuracy depends on the quality and units of the entered data.
• The equation may not be validated in every patient population.
• This tool does not replace clinical judgement or specialist advice.

Clinical Pearls

• Check units before calculating.
• Document the source and timing of each input.
• Use trends where clinically appropriate.

Common Mistakes

• Mixing SI and conventional units.
• Using non-contemporaneous measurements.
• Treating the output as a diagnosis or prescription.

Evidence Base

The implemented calculation follows the published or guideline-based relationship: 100 mL/kg for first 10 kg, 50 mL/kg for next 10 kg, then 20 mL/kg.

References

1. Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957. — Primary publication, guideline or established source supporting the calculation.