Water Intake Calculator — Daily Hydration Needs
The Water Intake Calculator tells you exactly how much water you should drink each day based on your body weight and activity level. Proper hydration is essential for energy levels, metabolism, kidney function, skin health, and nearly every system in your body. The commonly cited '8 glasses a day' is a rough guideline — your actual needs depend on your size and how much you move. Use this free calculator to get a personalized daily hydration target.
How to Use This Calculator
- 1
Enter your body weight in kilograms.
- 2
Select your typical daily activity level.
- 3
Click Calculate.
- 4
Your recommended daily water intake will be shown in liters and cups.
Frequently Asked Questions
A common formula is 30–40 mL per kilogram of body weight, adjusted for activity level. For example, a 70 kg person who is moderately active needs approximately 70 × 35 = 2,450 mL ≈ 2.5 liters per day.