Exercise Sweat Rate Estimate

Estimate fluid loss from mass change, drinking and urine.

Your numbers

Estimated sweat rate

—

Approximation treats 1 kg mass change as 1 L and omits respiratory/metabolic changes. This is not a fluid or sodium intake prescription.

Health inputs stay in this tab. Link sharing is disabled.

Formula

Estimate L = A−B+D−U and R = L/t. A and B are pre- and post-exercise mass in kg; D and U are drink and urine volumes in L; t is hours. The approximation treats a kilogram of mass change as a litre of fluid; R is in L/h.

Estimate fluid loss from mass change, drinking and urine.

Worked example

Pre-exercise mass (kg): 75
Post-exercise mass (kg): 74.5
Fluid consumed (L): 0.5
Urine produced (L): 0
Exercise duration (hours): 1

Estimated sweat rate: 1 L/h
Estimated sweat loss: 1 L

Scope and limitations

Approximation treats 1 kg mass change as 1 L and omits respiratory/metabolic changes. This is not a fluid or sodium intake prescription.

Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.

Check your units and assumptions before relying on a result. Changing a label does not convert a currency or physical unit.

Formula version: 160122f3e340 · Example checked: 2026-10-30

Methodology