Water Intake Calculator

Find out how much water your body needs each day based on your body weight and activity level, in litres and standard glasses.

Daily hydration target & glass pacing.

Weight

Activity Level

Exercise 3–5 days/week

Daily water intake

Your kidneys can process about 0.8–1 litre per hour — spread your intake through the day rather than drinking large amounts at once.

What is this water intake calculator based on?

It scales a clinically-cited adequate-intake range — roughly 30 ml/kg of body weight for a sedentary person up to 40 ml/kg for someone very active — by your own weight and activity level. More activity means more fluid loss through sweat, so the per-kg rate rises with it.

Worked Example — 70 kg, Moderate activity

2.45 litres/day2,450 ml · about 9.8 glasses (250 ml each)

Common Mistakes to Avoid

This is weight and activity only — not age, sex, or climate. Hot weather, illness, and individual differences all change real needs; treat the result as a starting baseline, not an exact prescription.
Pregnancy, breastfeeding, and creatine use aren't factored in. All three genuinely increase water needs beyond this formula — use this as a baseline and add to it based on your doctor's or a nutrition guide's specific advice.
More water isn't unlimited water. Drinking far beyond your calculated need doesn't add benefit and, in extreme excess, can be harmful — this number is a target, not a floor to exceed.