DocomintWater Intake Calculator
Calculate a daily hydration target in liters, cups, and ounces based on weight and activity.
A commonly cited hydration guideline scales water needs to body weight (about 33ml per kilogram per day) rather than the flat "8 glasses a day" rule of thumb, then adjusts upward for activity level — more movement means more fluid lost to sweat that needs replacing.
Example: A 70kg person with a moderate activity level has a target of about 2.54 liters/day — roughly 10.7 cups or 86 ounces, adjustable further for hot climates or heavier exercise days.
How it works
- Enter your weight and activity level
- Press Calculate
- A daily water intake target appears instantly in liters, cups, and ounces, computed on your device
Frequently asked questions
Is the "8 glasses a day" rule accurate?
It's a rough, easy-to-remember rule of thumb, not based on individual body size — scaling water intake to body weight (as this calculator does) is a more individualized estimate, though actual needs still vary by climate, diet, and activity.
Does this count water from food and other beverages?
No — this estimates a target for water specifically. In practice, food (especially fruits and vegetables) and other beverages also contribute meaningfully to total daily fluid intake, so this target is a reasonable ceiling rather than the only source that counts.
Is my numbers uploaded anywhere?
No — Water Intake Calculator runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.