How to use the Water Intake Calculator
- Enter your weight.
- Enter how many minutes you exercise on a typical day.
- Choose your climate.
- Read your daily target in liters, ounces and glasses.
What does this tool do?
Water needs vary a lot between people. A common starting point is about 30–35 ml per kilogram of body weight, plus extra for exercise and hot weather. The European Food Safety Authority suggests total water intake of about 2.0 liters a day for women and 2.5 liters for men, including water from food.
Why use it?
- Personal target instead of a generic “8 glasses”.
- Accounts for exercise and heat.
- Shown in liters, ounces and glasses.
Example
A 70 kg adult who exercises 30 minutes a day in a mild climate: 70 × 0.033 = 2.31 L, plus 0.35 L for exercise ≈ 2.7 L a day, or about 11 glasses of 250 ml.
The formula
Base = weight (kg) × 0.033 L
+ 0.35 L per 30 min of exercise
+ 0.5 L in hot or humid weather
Accuracy and limits
- This is a general estimate for healthy adults, not medical advice. Talk to a doctor or registered dietitian about your own situation.
- People with kidney, heart or liver conditions may need to limit fluids — follow your doctor's advice.
Privacy
The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.
Last reviewed by the M2Toolkit team.