How much water do you actually need?
Not eight glasses for everyone — your weight, workouts and the weather set your real number. Get a personalized daily target in seconds.
Get your daily target
33 ml per kilo, then adjust
The working clinical rule is roughly 30–35 ml per kg of body weight daily, plus ~350 ml per half hour of exercise, plus extra for hot climates — which is why the flat "8 glasses" rule fits almost nobody. A 55 kg woman and a 95 kg man do not need the same water.
Urine colour is the best everyday gauge: pale yellow means well-hydrated. Two medical caveats: kidney-stone patients are often told to drink more than this target, while people with heart failure or kidney disease may have fluid restrictions — for either, your doctor's number overrides any calculator's.
These results are indicative wellness estimates based on standard published formulas — not a diagnosis or medical advice. Always consult your doctor for clinical decisions. Fluid needs change with kidney, heart and liver conditions — follow your physician's guidance.
Frequently asked questions
Mostly yes — the diuretic effect of normal caffeine intake is mild, and all beverages plus food moisture contribute. Water remains the best default because it adds no sugar.
Yes — excessive rapid intake can dilute blood sodium (hyponatremia), a real risk in endurance sports. Spread intake through the day and let thirst lead; forcing litres at once helps nobody.
No — the calculation runs in your browser and nothing is transmitted.
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