How to use it
Fill in the fields - the answer updates as you type. Work out how much water to drink a day from your weight, exercise and the weather - in litres, glasses and ounces.
Free and private
The calculation runs in your browser. Nothing you type is sent or stored, and there is no limit.
Questions
How much water should I drink?
Roughly 33 ml per kg of body weight, plus about 350 ml for every 30 minutes of exercise and more in hot weather.
Is it free?
Yes - free and unlimited, with no sign-up.