Water Intake Calculator
Enter your weight and daily exercise minutes to see a recommended daily water intake in liters, cups, and fluid ounces.
Your calculation is performed in your browser.This result is an estimate for informational and educational purposes. It isn’t a diagnosis and isn’t a substitute for advice from a doctor, registered dietitian, or other qualified professional. See our methodology and sources for the formula used and its limitations.
How it works
The calculator uses a commonly cited baseline of about 33 ml of water per kilogram of body weight per day, then adds extra water for time spent exercising, since sweat losses increase fluid needs.
Formula & methodology
A baseline of 33 ml per kilogram of body weight is used, then 350 ml is added for every 30 minutes of exercise. This is a common rule of thumb; needs also change with heat, altitude, illness and diet.
Baseline (ml) = Weight (kg) × 33Exercise (ml) = (Exercise minutes ÷ 30) × 350Water (ml) = Baseline + ExerciseWhat each term means
- Litres
- Divide the millilitres by 1,000.
- Cups
- Divide the millilitres by 240.
- Fluid ounces
- Divide the millilitres by 29.57.
Worked example
A 70 kg person who exercises for 45 minutes needs roughly 2.8 liters (about 12 cups) of water per day.
Common uses
- —Setting a personalized daily water target instead of relying on the generic “8 glasses” rule.
- —Adjusting fluid intake around exercise days or hot weather.
- —Supporting a weight loss or fitness plan with an appropriate hydration baseline.
Important notes
- —This is a general estimate — climate, individual sweat rate, and overall diet (including water from food) all affect real hydration needs.
- —Thirst, urine color, and how you feel are useful everyday indicators alongside any calculated target.