Water Intake Calculator
How to work out how much water to drink
- Enter your weight in kg or lb.
- Add how many minutes you exercise on a typical day, and tick hot or humid weather if that applies.
- Read the daily total in liters, glasses, cups and ounces. Each glass drawn is 250 ml.
Frequently asked questions
How is it worked out?
It starts from a common rule of thumb of 35 ml per kilogram of body weight, then adds 350 ml for each 30 minutes of exercise and 500 ml for hot or humid weather. For 70 kg and 30 minutes of exercise that is 2,450 + 350 = 2,800 ml, about 2.8 liters or 11 glasses.
Do food and other drinks count?
Yes. Tea, coffee, milk, soup and watery food such as fruit all add to your water. The US National Academies put total water for adults at about 3.7 liters a day for men and 2.7 liters for women, from all drinks and food.
Who should not go by this?
People with kidney, heart or liver disease, or anyone told to limit fluids, should follow their doctor's advice instead. Drinking far more than you need can be harmful too.