How we estimate your daily water
This calculator uses a widely used rule of thumb: 33 ml of water for every kilogram of body weight. It then adds 350 ml for every 30 minutes of exercise, half a litre if the weather is hot, a little less if it is cool, and a small extra if you are pregnant or breastfeeding. The result is the amount of fluid you should aim to drink in a day, including tea, milk and other drinks.
Example
A 70 kg person who exercises 30 minutes in normal weather needs about 0.033 × 70 = 2.31 litres plus 0.35 litres for exercise, which is about 2.7 litres, or 11 glasses of 250 ml.
Tips to drink enough
- Drink a glass when you wake up and one with every meal.
- Keep a bottle on your desk and refill it at set times. The plan above spaces your glasses evenly.
- In hot summers, carry water when you go out and drink before you feel thirsty.
Check your weight status with the BMI Calculator and your daily energy with the Calorie Calculator.
Frequently asked questions
How much water should I drink per day?
A common rule of thumb is about 33 ml per kilogram of body weight. A 70 kg adult needs roughly 2.3 litres a day from drinks, more if they exercise or live in hot weather. Food also provides some water.
Does tea or juice count?
Yes, tea, milk, lassi and juice count towards your fluids, but plain water is best because it has no sugar or calories. Limit sweet drinks and soft drinks.
How much more should I drink in hot weather?
In hot weather and when sweating a lot, add about half a litre or more. The 'Hot' option adds 0.5 litre. Add a pinch of salt or use ORS if you are sweating heavily or have diarrhoea.
How do I know I am drinking enough?
Pale yellow urine is a good sign. Dark urine, headache, dry mouth and tiredness suggest you need more fluids. Spread your drinks through the day instead of drinking a lot at once.
Can I drink too much water?
Yes, but it is rare. Drinking many litres in a short time can dilute the body's salts. Sip regularly and follow your thirst and your doctor's advice.