Free online daily water intake calculator. Calculate science-based hydration needs based on weight, activity level, and temperature. Supports ml and oz switching.
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Adults should drink approximately 30-40ml per kg of body weight. Example: 70kg person needs 2100-2800ml daily. Add 500-1000ml for exercise or hot weather.
Base intake = weight(kg) × 35ml. Activity bonus: light +500ml, moderate +750ml, intense +1000ml. Hot climate adds 300-500ml.
Yes, excessive water intake can cause hyponatremia (water intoxication). Kidneys process 800-1000ml per hour max. Drink small amounts throughout the day.
Tea and coffee can count toward water intake, but caffeine is a diuretic. Limit to 50% of daily intake. Pure water remains the best hydration source.