Tools that pair well with this one.
Eight more calculators families use alongside this — all free, no account needed.
Water intake calculators
Water intake — frequently asked
How much water should I drink a day?+
A common guide is about 30–35 ml per kg of body weight — roughly 2–3 litres for most adults — adjusted up for activity and hot weather. The calculator personalises this from your weight, activity level and climate. Thirst and pale-yellow urine are good everyday signals you're well hydrated.
Does the '8 glasses a day' rule apply to everyone?+
It's a rough average, not a rule. Your real need depends on body size, activity, climate, pregnancy and health. In India's hot months you'll need more. Use the calculator for a personalised figure rather than a fixed number of glasses.
Do tea, coffee and food count toward hydration?+
Yes. Around 20% of your fluid typically comes from food, and tea and coffee do count despite their mild diuretic effect. The calculator estimates total water need; you don't have to get all of it from plain water.
Can you drink too much water?+
Rarely, but yes — drinking far more than you need can dilute blood sodium (hyponatraemia), which is dangerous. This mostly affects endurance athletes overdrinking. For most people, spreading normal intake through the day is safe.