Daily Water Intake
Your personalised hydration target based on weight, activity, and climate.
How much water should you drink?
The "eight glasses a day" rule ignores the two things that matter most: your body size and how much you sweat. This calculator starts from your body weight and then adjusts for your activity level and climate, giving you a target in litres, fluid ounces and cups.
Remember the figure includes water from all drinks, and roughly 20% of your daily water comes from food — so you don't need to drink the entire amount as plain water. If you train hard or sweat heavily, pair hydration with the electrolytes guide.
Frequently asked questions
How much water should I drink a day?
A common evidence-based starting point is about 30–40 ml per kilogram of body weight, adjusted up for exercise and hot climates. The calculator does this for you and reports the result in litres, ounces and cups.
Do coffee and tea count toward hydration?
Yes. Despite their mild diuretic effect, caffeinated drinks still contribute net fluid and count toward your daily total, as do most other beverages.
Can you drink too much water?
It is uncommon, but drinking extreme amounts in a short time can dilute blood sodium (hyponatraemia). Spread your intake through the day and, during long hard sessions, include electrolytes.