Sweat-rate and hydration calculator
Estimate your own fluid loss in under a minute.
Enter your pre- and post-session weight, fluid intake and session duration for an estimated hourly sweat rate, body-mass loss and practical hydration guidance.
Fill in your pre-session weight, post-session weight and session duration above to see your full report and get options to copy or share it.
This is a field-based estimate, not a laboratory or medical measurement. Individual results vary session to session with heat, humidity, intensity and effort. It does not replace professional or medical advice—use it as one input into a conversation with your coach.
