Water Intake Calculator
Calculate how much water to drink a day with this free online water intake calculator, based on weight, exercise and climate, plus a daily glass tracker.
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Part of the toolkit
How to use Water Intake Calculator
- 1Enter your body weight and how many minutes you exercise on a typical day
- 2Choose your sex and climate, and whether you're pregnant or breastfeeding
- 3See your daily target in liters or ounces, cups and bottles — then log glasses with the daily tracker
Frequently asked questions
How much water should I drink a day?▾
A common guideline is about 35 ml per kg of body weight (roughly half an ounce per pound) — around 2.5 L for a 70 kg adult — plus extra for exercise and hot weather.
How much water should I drink based on my weight?▾
Multiply your weight in kg by 35 ml: 60 kg → 2.1 L, 80 kg → 2.8 L, 100 kg → 3.5 L. In pounds, drink roughly 0.5–0.6 oz per pound of body weight.
How much more water do I need when exercising?▾
About 350 ml (12 oz) for every 30 minutes of activity, and more in heat or if you sweat heavily. Weighing yourself before and after exercise shows how much fluid you lost.
How much water should pregnant or breastfeeding women drink?▾
European guidance (EFSA) adds about 300 ml a day during pregnancy and about 700 ml while breastfeeding on top of the usual amount.
Do coffee, tea and food count toward water intake?▾
Yes. Tea, coffee, milk and water-rich foods like fruit, vegetables and soup all contribute — food usually supplies about 20% of total water. Plain water is still the best main source.
Can you drink too much water?▾
Yes. Drinking very large amounts in a short time can dilute blood sodium (hyponatremia). Spread your intake through the day and follow your doctor's advice if you have heart or kidney conditions.
Embed Water Intake Calculator on your website▾
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