Sweat Rate Calculator
Find out how much fluid your body loses per hour during exercise. This calculator estimates your sweat rate (L/hr), dehydration percentage, and the fluid volume needed to fully rehydrate after your workout.
Workout Measurements
To fully restore fluid balance, drink 1200 ml of water or electrolyte drink over the next 2-4 hours (150% of net weight loss).
How to use
- Enter your body weight before the workout (kg).
- Enter your body weight after the workout (kg).
- Enter the amount of fluid consumed during the workout (ml).
- Optionally, enter urine losses during exercise (ml).
- Enter the workout duration in minutes.
- Get your sweat rate, dehydration %, and rehydration recommendation.
What is sweat rate?
Sweat rate is the volume of fluid lost through sweat per hour of exercise. It varies with exercise intensity, ambient temperature, humidity, acclimatization level, and individual physiology. Knowing your sweat rate helps you plan optimal hydration strategies for training and competition.
How is sweat rate calculated?
Total sweat loss (ml) = (Pre-weight – Post-weight) × 1000 + Fluid consumed – Urine losses. Sweat rate (L/hr) = Total sweat loss ÷ Duration (min) × 60 ÷ 1000. Typical range: 0.5–2.5 L/hr depending on conditions.
Why does dehydration matter?
Losing just 2% of body weight through sweat can reduce athletic performance by 10–20%. At 5% dehydration, cramps, headache, and heat illness become real risks. Timely rehydration is essential for health and optimal training outcomes.
Frequently Asked Questions
How much should I drink during exercise?
Drink 150–250 ml every 15–20 minutes, adjusted for your calculated sweat rate. After exercise, aim to replace 150% of your fluid deficit (e.g., 750 ml for each 0.5 kg of weight lost).
What is the rehydration recommendation?
Post-exercise, consume 1.5 times the fluid lost (in weight terms) to account for ongoing losses. Electrolyte drinks are beneficial when sweat loss exceeds 1 litre.
Does temperature affect sweat rate?
Yes. In hot, humid conditions sweat rate can be 2–3 times higher than in cool environments. Always adjust your fluid intake plan when training outdoors in summer.
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