How much water do you need?
Personalized by weight, activity, and climate
Medical Disclaimer: This tool provides general educational estimates. Always consult your prescribing physician or healthcare provider before making medication changes or interpreting results from population-based models.
Frequently Asked Questions
The IOM recommends about 3.7L for men and 2.7L for women from all sources including food.
Yes. Coffee provides net positive hydration despite caffeine mild diuretic effect.
Yes. Excessive water can cause hyponatremia. Spread intake throughout the day.
Hot climates increase water needs by 20-30% due to increased sweating.
Sources
Methodology
This calculator uses a baseline of 35 ml per kg body weight (EFSA/IOM), multiplied by activity and climate factors. Age adjustment (-10% for 65+) is applied. The result represents drinking water intake, separate from the ~20% obtained from food.
Daily water needs depend on body weight, activity, and climate. The baseline is 35 ml per kg of body weight. A 70 kg moderately active person in temperate climate needs about 2.9 liters per day. Activity increases needs by 10-60%, hot climates by 20-30%. The IOM recommends 3.7L total for men and 2.7L for women from all sources. About 20% comes from food.
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