Maintenance Fluid (Holliday-Segar) Calculator
Calculate daily and hourly maintenance fluid requirements for paediatric and adult patients using the Holliday-Segar "4-2-1" rule.
Results
What is it?
The Holliday-Segar method calculates maintenance fluid requirements based on metabolic expenditure: 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 kg above 20 kg. The "4-2-1 rule" is the same formula expressed per hour: 4 mL/kg/hr for first 10 kg, 2 mL/kg/hr for next 10 kg, 1 mL/kg/hr above 20 kg.
How to use
Enter the patient's body weight in kilograms. The calculator applies the Holliday-Segar formula and outputs both daily and hourly fluid requirements. This represents the maintenance fluid only — additional losses (fever, surgery, burns, dehydration) require separate replacement calculation.
Example scenario
Child weighing 25 kg: first 10 kg → 1000 mL, next 10 kg → 500 mL, final 5 kg → 100 mL. Total = 1600 mL/day = 66.7 mL/hr. Using 4-2-1: 4×10 + 2×10 + 1×5 = 40+20+5 = 65 mL/hr (≈ same with rounding).
Pro tip
⚠️ For clinical use only with medical supervision. Standard maintenance fluid is typically 0.9% NaCl or Hartmann's solution in adults. Paediatric fluid choice should follow local guidelines. Avoid hypotonic solutions (0.18% NaCl) in surgical or critically ill children due to hyponatraemia risk.