Water Intake Calculator
How much water you should drink a day, by weight.
Reviewed by Zerunio’s medical team
A rough daily water target based on your body weight and activity. Your real needs shift with heat, exercise, illness, and pregnancy.
This tool gives general estimates for education only – it is not medical advice. Talk to a clinician about your health.
Frequently asked questions
How much water should I drink a day?
A rough guide is about 30 to 35 ml per kilogram of body weight, plus extra for exercise. For many adults that's around 2 to 3 litres, including fluids from food and other drinks.
Do tea, coffee and food count?
Yes. Most drinks and water-rich foods count toward your total. Moderate caffeine doesn't dehydrate you as much as people think.
Can you drink too much water?
Rarely, but drinking very large amounts fast can dangerously dilute your blood sodium. Spread your intake through the day.
How do I know if I'm drinking enough?
Pale-yellow urine and rarely feeling thirsty are good signs. Dark urine, headaches, or tiredness can mean you need more.