How much water do you need a day?
The European Food Safety Authority sets adequate total water intakes of about 2.0 litres a day for women and 2.5 litres for men in mild climates, at moderate activity. Roughly 20–30% of that usually comes from food — dal, sabzi, curd, fruit and rice all contain plenty of water — and the rest from drinks.
Bigger bodies, more sweating and hotter weather all raise that number, which is why this calculator starts from your weight (about 33 ml per kg) and adds to it for exercise and heat.
| Body weight | Litres | Glasses (250 ml) |
|---|---|---|
| 50 kg | 1.65 L | ≈ 7 |
| 60 kg | 2.0 L | ≈ 8 |
| 70 kg | 2.3 L | ≈ 9 |
| 80 kg | 2.65 L | ≈ 11 |
| 90 kg | 3.0 L | ≈ 12 |
Exercise and Indian summers
Sweat rates during exercise commonly range from 0.3 to over 2 litres an hour, depending on intensity, body size and heat. We add about 350 ml for every 30 minutes of training and another 500 ml for hot or humid weather — a reasonable middle estimate.
For long or very sweaty sessions, the American College of Sports Medicine suggests weighing yourself before and after: each kilo lost is about a litre of fluid to replace. In heat or after more than an hour of hard work, add salt — nimbu pani with a pinch of salt, chaas or ORS work well.
Signs you're drinking enough (or not)
| Sign | What it suggests |
|---|---|
| Pale straw-coloured urine | Well hydrated |
| Dark yellow urine, rarely needing to go | Drink more |
| Headache, tiredness, dizziness in heat | Possible dehydration — drink and rest in shade |
| Clear urine and going very often | You can likely drink a bit less |
What counts towards your water intake?
Almost every drink counts: water, chaas, lassi, nimbu pani, coconut water, milk, and even tea and coffee — moderate caffeine doesn't cause net fluid loss in regular drinkers. Watch the sugar, though: sweetened juices and soft drinks add calories fast.
Trying to lose weight? Drinking water before meals may help you feel fuller. See the calorie deficit calculator and Indian foods for weight loss.
Can you drink too much water?
Yes. Drinking very large amounts quickly — several litres in a few hours — can dilute blood sodium (hyponatraemia), which can be dangerous. It is rare in everyday life but does happen in endurance events. Spread drinks through the day and let thirst guide you. People with kidney, heart or liver conditions may need to limit fluids and should follow their doctor's advice.
Worked example: Sneha in Chennai
Sneha weighs 70 kg, trains for 45 minutes a day and lives in a hot, humid city.
Baseline: 70 × 33 ml ≈ 2.3 L. Exercise: 45 min ≈ +0.55 L. Heat: +0.5 L. Total: about 3.4 litres a day — roughly 13 glasses, from all drinks combined.
On rest days in an air-conditioned office, the same calculation gives about 2.3 L.
How this calculator works
Daily drinks = 33 ml × body weight (kg) + 350 ml per 30 minutes of exercise (up to 5 hours) + 500 ml for hot or humid climates. We add 300 ml during pregnancy and 700 ml while breastfeeding, in line with EFSA's increments. The total is rounded to the nearest 50 ml.
This is a starting estimate for healthy adults. Individual needs vary with sweat rate, diet and health, so adjust using thirst and urine colour.
Sources
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on Dietary Reference Values for water. EFSA Journal, 2010.
- American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc, 2007.
- Popkin BM, et al. Water, hydration, and health. Nutr Rev, 2010.
Frequently asked questions
Straight answers about this calculator. Educational only — not medical advice.
A practical rule of thumb is about 33 ml per kg of body weight from drinks — around 2.3 litres for a 70 kg adult — plus more for exercise and hot weather.
Not for most healthy adults, especially if you're active or live somewhere hot. It's only a concern if you have a condition that requires limiting fluids, or if you drink very large amounts in a short time.
Yes. In people who drink them regularly, moderate tea and coffee hydrate about as well as water. Keep added sugar low.
Water has no calories, and a glass before meals may help you feel fuller. Swapping sugary drinks for water is one of the easiest calorie cuts.
For sessions under an hour, sipping to thirst is usually enough. For longer or very sweaty sessions, aim to replace about a litre for every kilo of body weight lost, with some salt.
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This calculator provides an estimate and isn't a substitute for individualised medical or dietary advice. Read our medical disclaimer and editorial policy.