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Sweat Rate & Hydration Calculator
Estimate sweat rate and hourly fluid replacement needs from pre/post weight difference.
Fluids consumed during the session
Results
Total Sweat Loss1.50 L
Sweat Rate1.50 L/hr
Dehydration %1.3%
What is it?
This calculator measures your personal sweat rate by comparing pre- and post-exercise body weight adjusted for fluid intake.
How to use
Weigh yourself (nude) before and after exercise. Log any fluid consumed during. The calculator derives your sweat rate per hour.
Example scenario
Losing 1 kg and drinking 0.5 L over 60 minutes gives a sweat rate of 1.5 L/hr — high enough to require aggressive rehydration.
Pro tip
A >2% body weight loss from sweat significantly impairs performance. Aim to replace 80% of fluid losses during exercise.