Daily Water Intake Calculator
Estimate your daily water intake by weight and activity level — runs in your browser.
This is a general estimate. Individual hydration needs vary with climate, health status, and diet. Not medical advice — consult a healthcare professional if you have specific concerns.
How daily water intake is estimated
A widely used rule of thumb is 35 ml of water per kilogram of body weight per day — a middle value in the common clinical range of 30–40 ml/kg. This calculator applies that baseline and adds an activity bump (0 to 1,000 ml) for exercise-related fluid losses. One cup is defined as 240 ml. All computation runs in your browser with no data sent to a server.
Actual needs vary by climate, health status, and the water content of food (roughly 20% of daily intake typically comes from food). High temperatures, illness, pregnancy, and breastfeeding all increase requirements. The output here is a useful starting point, not a clinical prescription.
FAQ
Does coffee count? Yes. Despite mild diuretic effects, caffeinated drinks still contribute net fluid to your daily total at typical intake levels.
Is 8 glasses a day correct? The "8×8" rule is a popular heuristic but lacks strong scientific backing. Body-weight-based estimates are more individualised and generally more accurate.