Exercise raises your water needs fast — sometimes by more than a liter per workout. This water intake for exercise calculator adds your sweat losses to your daily baseline so you can rehydrate properly.
Exercise Hydration Calculator
Baseline (35 ml per kg) plus estimated sweat loss for your workout.
For information only — not medical advice.
How exercise changes your needs
When you work out, your body cools itself by sweating — and sweat is mostly water. Depending on intensity, you can lose roughly 0.4 to 1.2 liters per hour. This calculator adds an estimate of that sweat loss to your daily baseline (35 ml per kg of body weight) so your workout-day target reflects the real demand.
Smart hydration timing
- 2 hours before: drink 1–2 glasses of water.
- During: sip every 15–20 minutes — do not wait until you feel thirsty.
- After: drink 1–2 glasses within 30 minutes, more after long or hot sessions.
- Over 60–90 minutes: consider an electrolyte drink to replace sodium lost in sweat.
For information only — not medical advice. Endurance athletes and people with health conditions should follow guidance from a qualified professional.