Sweat Rate Calculator (Athlete Hydration)

Enter your body weight before and after exercise, exercise duration, and fluid intake during exercise to estimate your sweat rate.

Sweat Rate Calculator (Athlete Hydration)

Estimate your sweat rate during exercise from your pre- and post-exercise body weight.

This is an estimate for general informational purposes only, not medical advice. Sweat rate varies significantly with heat, humidity, exercise intensity and individual physiology — use it as a general planning guide, and consult a sports medicine professional for personalized hydration strategies, especially for endurance events.

Sweat rate estimates how much fluid you lose per hour of exercise, based on the change in your body weight, any fluid you drank during the session, and how long you exercised — useful for planning fluid intake during future training or events.

Example

  • With the default values shown above, this calculator returns: Total Fluid Loss (L) ≈ 1.70; Sweat Rate (L/hour) ≈ 1.13.

Frequently Asked Questions

Why does fluid intake during exercise get added back?

Any fluid you drank during exercise offset some of the weight you would have otherwise lost — adding it back to the weight loss gives your true total fluid loss from sweating.

What should I do with my sweat rate number?

Many athletes use their sweat rate to plan how much fluid to drink per hour during similar future exercise sessions to stay adequately hydrated, though individual tolerance and conditions still matter.

Sources

Related Calculators

Heart Rate Zone CalculatorCalculate your target heart rate zones for moderate and vigorous exercise using the Karvonen method.Hydration Needs by Weight CalculatorEstimates a general daily water intake target based on your body weight.
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