Water Intake Calculator
Estimate your daily water needs from body weight, exercise and climate, in litres, fluid ounces and glasses, compared with EFSA and US reference intakes.
Results
- Estimate: 35 mL per kg of body weight + 350 mL per 30 minutes of exercise + 500 mL in hot weather. This includes water from food and all drinks.
- Reference total water intakes: EFSA 2.5 L (men) / 2.0 L (women); US National Academies 3.7 L / 2.7 L. Needs differ with health conditions, pregnancy and breastfeeding.
What is Water Intake Calculator?
Gives a transparent estimate of daily total water needs based on body weight, minutes of exercise and hot weather, in litres, US fluid ounces and 250 mL glasses. Official reference intakes from EFSA and the US National Academies are shown alongside for comparison.
How to use Water Intake Calculator
- Choose units and Sex, and enter your Weight.
- Enter daily Exercise minutes and choose the Climate.
- Read the estimate and compare it with the reference intake.
Example
70 kg, 30 minutes of exercise, temperate climate
2.8 L per day (2,800 mL, 94.7 fl oz, 11.2 glasses)
When to use Water Intake Calculator
Use it as a general guide for healthy adults. People with heart or kidney conditions, pregnant or breastfeeding women and endurance athletes have different needs and should follow medical advice.
How Water Intake Calculator works
Estimate = 35 mL per kg of body weight + 350 mL per 30 minutes of exercise + 500 mL in hot or humid weather. This is a common rule-of-thumb, not an official standard. Reference total water intakes (from all food and drinks): EFSA 2.5 L for men and 2.0 L for women; US National Academies 3.7 L and 2.7 L. About 20–30% of total water usually comes from food.
Common Use Cases
- Setting a daily hydration goal
- Adjusting intake for training days
- Planning water for hot-weather hikes
- Comparing personal needs with official references
FAQs
Do coffee and tea count?
Yes, all drinks contribute to total water intake, as does water in food.
Is 8 glasses a day correct?
It is a rough rule close to the EFSA reference for women; needs vary with body size, activity and climate.
Can I drink too much water?
Yes, very large amounts in a short time can cause hyponatremia. Spread intake through the day.