Water Intake Calculator
About the Water Intake Calculator
Estimate how much water to drink each day based on your body weight, how long you exercise, and your climate. The result is shown in litres and as an approximate number of 250 ml glasses so it is easy to act on. This is a general guide for healthy adults, not a medical prescription — thirst, urine colour, and your doctor’s advice are still the best day-to-day signals.
This tool works in your browser: the files and text you use are processed on your device and are not uploaded.
How to use it
- Enter your body weight in kilograms.
- Add your typical daily active-exercise minutes.
- Choose mild or hot climate, then read your daily hydration target.
Frequently asked questions
How is the daily water goal calculated?
The tool starts from about 35 ml of water per kilogram of body weight, adds roughly 11.5 ml for every minute of active exercise, and adds a further 500 ml in a hot or tropical climate. The total is shown in litres and as ~250 ml glasses.
Does food and other drinks count toward this?
The estimate covers total water intake, and food (especially fruit and vegetables) typically supplies around 20% of it. Tea, coffee, and milk also contribute. Treat the number as total fluids, not water you must drink on top of everything else.
Can you drink too much water?
Rarely, but yes — drinking far more than you need in a short time can dangerously dilute blood sodium (hyponatraemia). Spread intake across the day and let thirst guide you rather than forcing large volumes at once.
Do I need more water when it is hot or during exercise?
Yes. Sweat losses rise sharply with heat and activity, which is exactly why the calculator adds extra for exercise minutes and a hot climate. On very intense or long sessions, also replace electrolytes, not just water.
This tool provides general estimates for informational purposes only and is not medical advice. Always consult a qualified healthcare professional about your health, diet, or pregnancy.