How to use the Water Intake Calculator
Enter the body weight and exercise per day and the result appears straight away. Everything runs in your browser, so nothing you type is uploaded.
The formula
Litres = 0.033 × kg + 0.35 per 30 minutes of exercise (+0.5 in hot weather)
Examples
- 70 kg, 30 minutes of exercise, mild climate
Daily water: 2.7 litres (90 fl oz, about 11 cups of 250 ml) This includes water from food and other drinks.
- 70 kg, 60 minutes of exercise
Daily water: 3.0 litres (102 fl oz, about 12 cups of 250 ml) This includes water from food and other drinks.
- 85 kg, 45 minutes of exercise
Daily water: 3.3 litres (113 fl oz, about 13 cups of 250 ml) This includes water from food and other drinks.
Limitations and assumptions
Needs also come from food and vary with health, pregnancy and medication. General estimate for adults, not medical advice. Speak to a doctor or registered dietitian before making significant changes to diet, exercise or health routines.
Frequently asked questions
How much water should I drink a day?
Common guidance is around 30 to 35 ml per kg of body weight, plus extra for exercise and heat.
Does food count?
Yes, a share of daily fluid comes from food and other drinks.
Can I drink too much?
Yes, though it is rare. Excess water can dilute blood sodium.
Is this medical advice?
No. Ask a doctor if you have a kidney, heart or other condition.