Calculate daily water intake
Estimate how much water to drink daily based on body weight and activity level.
A general estimate (35ml per kg of body weight, plus 350ml per 30 minutes of exercise). Actual needs vary with climate, health conditions, and what you eat.
Metric or imperial. The base intake scales with body weight.
Every complete 30 minutes adds 350ml on top of the base amount.
Shown in litres, glasses, and a base-vs-exercise breakdown.
Frequently asked
How is the base amount calculated?
35ml per kilogram of body weight. A common rule-of-thumb baseline used by nutrition guidelines, before accounting for activity, climate, or health conditions.
Does this include water from food and other drinks?
No. This is a target for water specifically. Food and other beverages also contribute to daily hydration, so your total fluid intake from all sources will typically be somewhat higher than this number.
Should I drink more in hot weather or at altitude?
Likely yes. This calculator doesn't account for climate, altitude, or sweat rate, all of which increase fluid needs. Treat the result as a baseline to adjust upward in those conditions.
Is this medical advice?
No. It's a general-purpose estimate for informational purposes only, not medical advice. People with kidney, heart, or other conditions that affect fluid balance should follow guidance from their healthcare provider instead.