Fluid Balance Calculator
Fluid Intake & Output Balance
Calculate net fluid balance from intake and output totals
mL
mL
mL
mL
mL
kg
hours
Maintenance Fluid Calculation (4-2-1 Rule)
Calculate maintenance IV fluid rate using the Holliday-Segar method
kg
Formula
Net balance = Total intake - Total output | Adjusted balance = Total intake - (Measured output + Insensible losses) | Insensible losses ~10 mL/kg/day | 4-2-1 rule: 4 mL/kg/hr (first 10 kg) + 2 mL/kg/hr (next 10 kg) + 1 mL/kg/hr (remaining kg)
Frequently Asked Questions
What is fluid balance?
Fluid balance is the difference between total fluid intake and total fluid output over a period (usually 24 hours). A positive balance means more intake than output; negative means more output than intake.
What is the 4-2-1 rule?
The 4-2-1 rule (Holliday-Segar method) calculates maintenance IV fluid rates: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for each kg above 20 kg.
What is oliguria?
Oliguria is urine output less than 0.5 mL/kg/hr in adults (or <1 mL/kg/hr in children). It may indicate dehydration, acute kidney injury, or decreased renal perfusion. It requires clinical evaluation.
What are insensible losses?
Insensible losses are fluid lost through skin evaporation and respiration that cannot be measured. They average about 10 mL/kg/day in adults but increase with fever, tachypnea, burns, and low humidity.
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