Water Intake Calculator
Estimate how much water to drink daily from your weight and activity.
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How it works
A common guideline puts daily water needs at roughly 35 millilitres per kilogram of body weight. The tool starts from your weight, adds an allowance for exercise (about 350 ml per 30 minutes of activity), and an optional adjustment for a hot climate. The result is shown in litres along with everyday equivalents: 8-ounce cups, fluid ounces, and half-litre bottles. These are general estimates — your real needs depend on health, diet, and conditions. Everything is calculated locally in your browser.
baseline (ml) ≈ 35 × weight(kg)
+ ~350 ml per 30 min exercise
Common use cases
- Setting a daily hydration goal based on your body weight.
- Adjusting water intake on heavy workout or hot-weather days.
- Translating a litre target into cups or bottles to track easily.
Frequently asked questions
How is the estimate calculated?
It uses roughly 35 ml of water per kilogram of body weight as a baseline, then adds about 350 ml for each 30 minutes of exercise and an optional bump for hot climates.
Does food and other drinks count toward this?
Food, especially fruit and vegetables, and other beverages contribute to hydration — often around 20% of intake. This figure is a total-fluid guideline, so you need not drink all of it as plain water.
Is this medical advice?
No. It is a general estimate. Certain conditions, medications, pregnancy, and climates change fluid needs, so treat it as a starting point and consult a professional for medical guidance.