Sweat Rate Calculator
Work out how much you sweat per hour so you can plan hydration for training and racing.
How to use the sweat rate calculator
- Weigh yourself before and after a measured workout.
- Enter both weights, the fluid you drank, and the duration.
- Click Calculate to get your sweat rate and a fluid target.
Why sweat rate is individual
Sweat rates vary widely with fitness, heat acclimation, intensity and genetics. Measuring yours removes the guesswork and helps prevent both dehydration and over-drinking.
Frequently asked questions
How do you calculate sweat rate?
Sweat rate equals body-weight loss plus fluid consumed, divided by exercise time. A 1 kg drop after drinking 500 ml in an hour is a 1.5 L/hour sweat rate.
How much should I drink while running?
Aim to replace most of what you lose. Many runners need 400–800 ml per hour, but your own sweat rate — and the heat — should set the number.
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