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Estimates maintenance fluid rate using a weight-based method.
100 mL/kg for first 10 kg, 50 mL/kg for next 10 kg, 20 mL/kg thereafter
Variable by patient size and clinical needs
This is a common starting point for maintenance fluid planning.
Specialty
Internal MedicineCategory
Internal MedicineDifficulty
Basic
Estimated Time
30 seconds
Version
1.0
Last Updated
2026-07
Formula
Keywords
Normal Range
Variable by patient size and clinical needs
Estimates daily maintenance fluid volume using the weight-based 100/50/20 rule: 100 mL/kg for the first 10 kg, 50 mL/kg for the next 10 kg, and 20 mL/kg thereafter.
The 100/50/20 rule (Holliday-Segar) estimates maintenance water needs by body weight. For a 70 kg adult: 1,000 + 500 + 1,000 = 2,500 mL/day.
The Holliday-Segar 100/50/20 rule remains a widely taught and clinically used starting point for maintenance fluid volumes across children and adults.
A 70 kg adult needs an estimate of daily maintenance fluids.
Inputs:
Maintenance fluids = 100 mL/kg × 10 kg + 50 mL/kg × 10 kg + 20 mL/kg × 50 kg = 2,500 mL/day.
The first 10 kg of body weight contributes 100 mL/kg/day, the second 10 kg 50 mL/kg/day, and every kilogram above 20 kg contributes 20 mL/kg/day. The three amounts are summed.
Divide the daily volume by 24. For 2,500 mL/day this is approximately 104 mL/hour.
Disclaimer: This calculator is intended for educational and clinical decision support purposes only. Maintenance fluid plans must account for clinical status, losses, and organ function.