Water Intake Calculator — By Weight & Activity
CalculatorA water intake calculator estimates a recommended daily fluid range using 30–35 ml per kilogram of body weight plus an addition for exercise time.
What is it
A common approximation for healthy adults is 30–35 ml of water per kilogram of body weight per day, adding 350–500 ml per 30 minutes of exercise. As official references, EFSA sets adequate total water intake (including food) at 2.0 L for adult women and 2.5 L for men, while the U.S. National Academies suggests 2.7 L and 3.7 L respectively. Actual needs vary with climate, sweating, and health status, so this is an informational estimate — people with kidney or heart conditions requiring fluid restriction must follow their doctor's instructions.
How to use
- 1Enter your body weight (kg).
- 2Enter daily exercise time in minutes, or 0 if none.
- 3Press calculate to see your recommended daily water intake range in litres.
Reference
| Reference | Amount |
|---|---|
| EFSA adequate intake — adult women (total water) | 2.0 L |
| EFSA adequate intake — adult men (total water) | 2.5 L |
| U.S. National Academies — adult women (total water) | 2.7 L |
| U.S. National Academies — adult men (total water) | 3.7 L |
| Weight approximation (70 kg, no exercise) | 2.1–2.5 L |
Sources & standards
- Scientific Opinion on Dietary Reference Values for water - European Food Safety Authority
- Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate - National Academies of Sciences
FAQ
How many litres of water should I drink per day?
About 2.1–2.5 L for a 70 kg adult (30–35 ml per kg of body weight). EFSA sets adequate total water intake, including food, at 2.0 L for women and 2.5 L for men.
How much extra should I drink when exercising?
A common guideline is an extra 350–500 ml per 30 minutes of exercise, increased further in hot weather or with heavy sweating.
Do coffee and food count toward the total?
Yes. EFSA and U.S. National Academies values are total water including food and all beverages; roughly 70–80% of total water typically comes from drinks.
Is my weight data sent to a server?
No. This calculator runs entirely in your browser and does not send or store your inputs.