Sweat Rate Calculator
Your sweat rate during exercise from pre/post-exercise weight and fluid intake.
Every calculation runs locally in your browser. Sweat rate varies with heat, humidity, and effort — a single session isn't necessarily representative of every workout.
Total sweat loss
2.2 L
Sweat rate
1.1 L/hour
For informational and educational purposes only — not medical advice, and not a substitute for consulting a qualified professional about your specific situation. TrueMeasureKit is not liable for decisions made based on these results. See our Terms of Service.
Why weight change alone isn't the full picture
Body weight lost during exercise isn't purely sweat — some of it is offset by fluid drunk during the session, and reduced by any urine produced. Sports scientists use this same weigh-before, weigh-after method (with athletes typically weighed nude or in minimal, dry clothing for accuracy) to calculate a personal sweat rate, which is then used to plan how much fluid to drink per hour during similar future efforts to stay close to hydration-neutral.
Frequently asked questions
Why does body weight change alone not equal sweat loss?
Some of the weight lost during exercise is offset by fluids you drank, and further reduced by any urine produced — so sports scientists subtract fluid intake and add back urine output to isolate the actual sweat loss.
How should I use my sweat rate once I know it?
It's the basis for a personal hydration plan during exercise — aiming to drink roughly what you lose per hour helps you stay close to hydration-neutral during similar future efforts in similar conditions.