Fluid Requirement Calculator
Calculate daily maintenance fluid requirements using the Holliday-Segar method.
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How to use this calculator
The Holliday-Segar method calculates the minimum fluid needed to cover daily insensible losses, urine output, and metabolic needs. It was originally derived from caloric expenditure data: roughly 100 mL of fluid is needed per 100 calories burned.
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Enter the patient's body weight in kilograms.
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The calculator applies the Holliday-Segar formula automatically.
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Use the daily total to plan oral or IV fluid replacement.
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Adjust the calculated rate up or down for clinical factors like fever, losses, or renal disease.
Frequently asked questions
What is the Holliday-Segar method?
Developed by Drs Malcolm Holliday and William Segar in 1957, this formula calculates maintenance fluid needs based on body weight. It is the most widely used formula for paediatric fluid management and is also applied to adults as a starting point.
Does this account for ongoing losses?
No. This formula calculates maintenance fluids only — the baseline volume needed to replace normal daily losses. Additional fluids must be added separately to replace losses from vomiting, diarrhoea, surgical drains, or fever (add ~12% per degree Celsius above 37.5°C).
Is this formula used for adults too?
Yes. While developed for children, the Holliday-Segar formula is commonly used for adults as an initial guide. For a 70 kg adult it gives approximately 2,500 mL/day, which aligns with standard adult fluid recommendations.
Should I use this for patients with heart failure or renal disease?
This formula provides a starting estimate only. Patients with heart failure, chronic kidney disease, cirrhosis, or other conditions affecting fluid balance require individualised fluid management under close clinical monitoring.
Fluid Requirement Calculator — Holliday-Segar Method
How the Holliday-Segar Formula Works
The formula divides body weight into three ranges, each with a different fluid rate per kilogram. For the first 10 kg, the metabolic rate (and therefore fluid need) is highest at 100 mL/kg/day. For the next 10 kg (10–20 kg) it decreases to 50 mL/kg/day, and for every kilogram above 20 kg it drops further to 20 mL/kg/day. This reflects the declining metabolic rate per unit body mass as weight increases.
Practical Clinical Application
In practice, the calculated daily volume is divided by 24 to get an hourly IV drip rate. A 20 kg child, for example, needs 1,500 mL/day — equivalent to approximately 62.5 mL/hr. This rate is then titrated based on urine output targets (typically 0.5–1 mL/kg/hr in children), electrolyte levels, and the presence of ongoing fluid losses.
Learn more from an authoritative source:
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →