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Water Intake Calculator

Estimate a daily water intake goal. The baseline uses ~35 ml per kilogram of body weight, then adds for activity level, hot-weather exposure, and pregnancy or lactation. See the total in millilitres, litres, US fluid ounces, and glasses (250 ml). Runs entirely in your browser.

Enter your weight to estimate daily water intake.

Baseline ≈ 35 ml per kg of body weight per day (a common guideline; the U.S. National Academies suggest ~3.7 L/day for men and ~2.7 L/day for women from all fluids). Additions: light +250 ml, moderate +500 ml, intense +1000 ml; hot +500 ml, very hot +1000 ml; pregnancy +300 ml, lactating +700 ml. About 20% of intake normally comes from food. This is a general estimate — thirst, climate, and medical conditions all matter; consult a provider for personal advice. Runs locally.