A weight-based answer to how much water you should drink daily, adjusted for exercise and climate.
What this calculator does
The honest answer is that it depends on your size, how much you sweat and how hot it is. This calculator turns those three variables into a number rather than repeating the eight-glasses rule.
Thirst is a reasonable guide for most healthy adults, and urine colour is a practical check — pale straw suggests adequate hydration.
Worked example
Worked through, a pregnant or breastfeeding of No produces a daily water target of 2,660 mL. Underneath, In litres comes out at 2.66 L and In US cups at 11.2 cups. Change any field and every figure updates as you type.
How to use it
- Enter your body weight.
- Enter typical daily exercise minutes.
- Select your climate and read the target.
Formula reference
daily water ≈ (weight in kg × 33 mL + exercise allowance) × climate factor
Common questions
Should I drink more in hot weather?
Yes — sweat losses rise sharply, and the climate setting here adds roughly 10–20%.
How do I know if I am drinking enough?
Pale straw urine and infrequent thirst are the usual practical signs for healthy adults.