Water Intake Calculator

How the target is built

The baseline is 33 mL per kilogram of body weight — the mid-point of common dietetic guidance (30–40 mL/kg). Exercise adds about 350 mL per 30 minutes to replace sweat, and hot climates add another 500 mL.

Frequently asked questions

Does coffee or tea count?

Yes — despite the myth, normal caffeinated drinks hydrate you; the mild diuretic effect doesn't cancel the fluid. Food counts too: roughly 20% of most people's water comes from meals.

Is "8 glasses a day" wrong?

It's a one-size-fits-all rule of thumb (~1.9 L). Needs scale with body size and sweat — a 90 kg runner in summer needs far more than a 55 kg office worker in winter.

Can you drink too much?

Yes — drinking many liters in a short time can dangerously dilute blood sodium (hyponatremia). Spread intake through the day and let thirst guide you during long exercise.

General guidance, not medical advice — kidney and heart conditions change fluid needs.