Water Intake Calculator

Estimate how much water to drink per day from your weight, exercise and climate.

Runs instantly in your browser — results update as you type.

How much water should I drink a day?

A practical estimate is about 33 ml per kilogram of body weight, plus about 350 ml for every 30 minutes of exercise and around 0.5 litres more in hot weather. A 70 kg adult with 30 minutes of exercise needs roughly 2.7 litres from drinks and food.

Reference values

The European Food Safety Authority suggests about 2.0 litres a day for women and 2.5 litres for men from all sources, of which roughly 20% comes from food. Pale-yellow urine is a simple sign you are drinking enough.

Frequently asked questions

Do tea and coffee count?

Yes, they count toward your fluid intake.

Can I drink too much water?

Yes, very large amounts in a short time can be dangerous (hyponatraemia).

Is this medical advice?

No — people with heart or kidney conditions should follow their doctor.