Health & Fitness
Hydration Sweat Rate Calculator
Estimate sweat rate and fluid replacement needs from pre/post-exercise weight and fluid intake.
Preparing your result…
What this calculator does
Calculates Hydration Sweat Rate Calculator using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
Sweat loss (L) ≈ weight before − weight after (kg) + fluid drunk (L) − urine passed (L); sweat rate = loss ÷ hours
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • Sweat loss L≈pre-exercise mass kg−post-exercise mass kg+fluid consumed L−urine passed L. Sweat rate L/hour=sweat loss/duration hours. The kg-to-L approximation assumes water density about 1 kg/L.
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • Original omits urine loss. Add urine input or explicitly limit to no urine during the test; use consistent clothing/dry weighing. Other mass exchange matters in long sessions. Sweat rate is not automatically the volume that should be drunk each hour.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Weight before (dry, minimal clothing) (kg) | Weight after (dried off) (kg) | Fluid drunk during (L) | Sweat rate |
|---|---|---|---|---|
| Worked example | 70 | 69.2 | 0.5 | 1.3 L/hour |
| Half the amounts | 35 | 34.6 | 0.25 | 1.3 L/hour |
| Double the amounts | 140 | 138.4 | 1 | 1.3 L/hour |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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