Why knowing your sweat rate matters

Understanding your sweat rate is one of the most powerful tools to personalise your hydration strategy. It tells you exactly how much fluid you're losing per hour during exercise. Helping you avoid dehydration, reduce the risk of cramps, maintain performance, and recover more efficiently after long sessions or races.

Every runner is different, and your sweat rate can change depending on the weather, your pace, and your effort. That’s why measuring it gives you a clear advantage, especially for endurance and ultra events.

How to use this sweat rate calculator

To get the most accurate result, follow these steps during your next training session or race simulation:

1. Weigh yourself nude (or with minimal clothing) before your run. Record your weight in kilograms.

2. Track all fluids you drink during your run (in litres).

3. Track any food you eat during the run (in grams, convert to kilograms by dividing by 1000).

4. If you urinate during your run, estimate the volume in litres.

5. Weigh yourself nude again immediately after your run.

6. Record the duration of your run in hours (e.g., 1 hour 30 minutes = 1.5 hours).

7. Enter your numbers below and hit "Calculate Sweat Rate".

Your result will show your sweat rate in litres per hour.