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Fluid Balance Calculator

Work out fluid balance instantly with clear inputs, formula shown and shareable results.

About Fluid Balance Calculator

Subtracts measured output and insensible losses from total intake to give the net fluid balance over the charting period.

Formula

Fluid balance

Net balance = intake - measured output - insensible losses; insensible losses are roughly 0.5 mL/kg/h and rise with fever

Worked example

With the default values below, Fluid Balance Calculator returns Net fluid balance of 100. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total intakeaccepts 0–15,000 mL
2,400 mL
Measured outputaccepts 0–15,000 mL
1,800 mL
Insensible lossesaccepts 0–3,000 mL
500 mL

Results

Net fluid balance
100 mL
Balance before insensible losses
600 mL
Direction
Approximately even

Step by step

  1. 1Values used
  2. 2Fluid balance
  3. 3Net fluid balance= 100 mL
  4. 4Balance before insensible losses= 600 mL
  5. 5Direction= Approximately even

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

What counts as insensible loss?

Evaporation from skin and the respiratory tract, typically 500 to 800 mL a day in an adult and more with fever.

Does weight change track balance?

Yes. One litre of fluid is about one kilogram, so daily weights are a useful cross-check on the chart.

Related Calculators

Fluid Balance Calculator – Calculate Net fluid balance