Does this include water from food?

Food provides roughly 20% of daily water for most people. The figure here is total water; you do not need to drink all of it as plain water.

Should I drink more in hot climates?

Yes. Heat and sweating raise needs significantly, as does altitude. Drink to thirst and watch urine colour — pale yellow is a good sign.

Can I drink too much water?

Yes. Excessive intake in a short time can cause hyponatraemia. Spread intake through the day rather than gulping large amounts at once.

Does this include water from food?

Food provides roughly 20% of daily water for most people. The figure here is total water, so you do not need to drink all of it as plain water — soups, fruit and vegetables count too.

Should I drink more in hot climates?

Yes. Heat, humidity and altitude all raise needs significantly, as does intense exercise. Drink to thirst and watch urine colour — pale yellow is a good sign that intake is about right.

Health & Fitness Calculators

Daily Water Intake Calculator

A common rule of thumb for hydration is about 35 ml of water per kilogram of body weight, plus extra for exercise. Individual needs vary with climate, diet, pregnancy and health, but this gives a sensible starting point.

Enter your body weight and the minutes of exercise you do a day. The calculator returns the recommended intake in litres and as a number of 250 ml glasses.

It gives a sensible daily target to aim for, then lets thirst and the colour of your urine fine-tune the actual amount on any given day.

Body weightkg

Daily exercisemin

Enter your values to see the result.

How this is calculated

This calculator estimates daily water intake from body weight and exercise. The base is about 35 ml of water per kilogram of body weight, which covers ordinary hydration needs. Exercise adds extra: for every 30 minutes of activity, 0.35 litres is added, reflecting the fluid lost through sweat and heavier breathing.

The result is shown both as a total in litres and as a number of 250 ml glasses, to make it easier to track across the day. Spreading intake through the day is better than drinking large amounts at once.

The model is a rule of thumb and does not adjust for climate (heat and humidity raise needs), altitude, pregnancy or breastfeeding, dietary salt or protein intake, caffeine and alcohol (which are mildly diuretic), or medical conditions such as kidney disease. About 20% of daily water normally comes from food, so you do not need to drink the entire figure as plain water. Drinking far more than needed in a short time can cause hyponatraemia, so pace intake rather than gulping.

Worked example

A 70 kg adult who exercises 30 minutes a day.

1Base intake = 70 × 0.035 = 2.45 L.
2Exercise extra = (30 ÷ 30) × 0.35 = 0.35 L.
3Total = 2.45 + 0.35 = 2.8 L, or about 11 glasses (250 ml each).

Frequently asked questions

Does this include water from food?: Food provides roughly 20% of daily water for most people. The figure here is total water; you do not need to drink all of it as plain water.
Should I drink more in hot climates?: Yes. Heat and sweating raise needs significantly, as does altitude. Drink to thirst and watch urine colour — pale yellow is a good sign.
Can I drink too much water?: Yes. Excessive intake in a short time can cause hyponatraemia. Spread intake through the day rather than gulping large amounts at once.
Does this include water from food?: Food provides roughly 20% of daily water for most people. The figure here is total water, so you do not need to drink all of it as plain water — soups, fruit and vegetables count too.
Should I drink more in hot climates?: Yes. Heat, humidity and altitude all raise needs significantly, as does intense exercise. Drink to thirst and watch urine colour — pale yellow is a good sign that intake is about right.

Related calculators

Method: 35 ml/kg body weight plus exercise allowance. No external data source. Last updated: September 2026.

These results are general estimates from established formulas and are not medical advice. They depend on the accuracy of the values you enter and on individual factors the formulas cannot capture. Consult a qualified healthcare professional before making decisions about your diet, training or treatment.