Tools · Fuel
Sweat rate calculator
Weigh yourself before and after a session, note what you drank, and see how much you sweat each hour and what to drink next time in the same conditions.
Weigh in the same minimal clothing, towel off first, and skip the toilet in between, or the number reads high.
Your sweat rate
Enter both weights and the session length to see your rate.
Educational, not medical advice. If you have diabetes, a heart condition or another medical condition, ask your doctor or a dietitian first.
How it works.
One kilogram of body weight lost during exercise is about one litre of sweat. Add what you drank, divide by the hours, and you have your sweat rate: the method the American College of Sports Medicine recommends.
Losing more than 2% of body weight is where endurance performance tends to suffer, above all in the heat. The aim is to drink enough to stay inside that, not to replace every drop: drinking far more than you sweat can dilute the sodium in your blood.
Sweat rate changes with heat, humidity, pace and fitness, so measure in the conditions you train or race in, and again when the season changes.
Sources
- Sawka MN, Burke LM, Eichner ER, et al. American College of Sports Medicine position stand: Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377–390.
- Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016;48(3):543–568.
From px Insights
Training in Hot Weather: How to Adjust Without Losing Your Week
Heat does not make you slower. It makes everything cost more. How to trade pace for effort, protect the week, and let your body adapt on schedule.
Fuel: A Training Nutrition Plan That Moves With Your Actual Training Load
A food log changes nothing on its own. How carbohydrate and protein should move with the training you actually do, and the nutrition rules you can safely drop.
Questions
What is a normal sweat rate?
The American College of Sports Medicine puts typical rates between about 0.3 and 2.4 litres an hour, depending on the person, the effort and the heat. The range is wide, which is why measuring your own beats any average.
How much should I drink during exercise?
Enough to keep your loss under 2% of body weight, and no more than you sweat. This calculator turns your own sweat rate into an amount per hour for similar conditions.
Do I need electrolytes?
For long sessions, heavy sweating or hot conditions, sodium in your drink helps you hold on to the fluid and replaces what you lose. For an hour in cool weather, water is usually enough.
Tomorrow morning, already decided.
Seven days free. By this time next week, px knows your normal.