Sweat Rate Calculator
Estimate how much you sweated during a workout. Save a few tests across different conditions so you can choose a useful result for your next session.
Calculate your sweat rate
Weigh yourself on the same scale just before and after a typical workout. Wear similar dry clothes each time.
Sweat rate preview
This is how much sweat you lost per hour in this session. Your rate may change on a hotter day or at a harder effort. Use the result as a guide when planning drinks, and adjust for thirst and comfort.
Session details for savingrunning, moderate effort
Your journal saves these details and the result on this device. You can remove any saved session below.
Safety: do not deliberately dehydrate, overdrink, or use this tool to “make weight.” If you have experienced heat illness, hyponatraemia, fainting, or unusually high losses, seek advice from an appropriately qualified clinician or sports dietitian.
Compare your saved sessions
See how your sweat rate changes on easy and hard days, or in different weather. Your last 24 saved sessions stay on this device.
Save a result after a typical workout. Next time, you can compare the two.
Why sweat rate changes
You might sweat differently on an easy run in cool weather and a hard ride on a hot day. Your size, how hard you go, the kit you wear and how used to the heat you are all affect the result.
The National Athletic Trainers’ Association recommends quantifying sweat rate in realistic environments and using the result as part of an individual plan that avoids both excessive dehydration and overdrinking. This calculator follows its published equation.
How to measure your sweat rate
- Use the same reliable scale immediately before and after exercise.
- Wear as little clothing as you can at both weigh-ins and towel off before the second one.
- Write down how much you drink during the session.
- Record urine passed when practical.
- Try the test in a few different conditions and compare your results.
Sweat-rate questions
What is a normal sweat rate?
Sweat rates vary a lot. Compare your own results from similar workouts to see what’s usual for you.
How do I calculate my sweat rate?
Work out how much weight you lost, add what you drank and subtract any urine you passed. Then divide the estimated litres lost by the number of hours you exercised.
Does sweat rate change in hot weather?
Yes. Temperature, humidity, sun, clothing, intensity and acclimatisation can all change sweat loss.
How often should I measure my sweat rate?
Try another test if you change activity, train harder, wear different kit or exercise in different weather. Keep a few results so you can choose the one that best matches your next session.
Do fitter people sweat more?
Training and acclimatisation can change sweating, but fitness alone cannot predict an individual rate. Try the test on a typical workout.