Fill in the details and click Calculate to see your results.
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📘 About the Daily Water Intake Calculator
A common rule is about 35 ml of water per kg of body weight a day (30 ml after 65). The European Food Safety Authority recommends 2.5 litres of total water a day for men and 2.0 litres for women — about 20% of it comes from food such as dal, rice, fruit and vegetables.
You need more when you exercise (roughly 350 ml for every 30 minutes), in hot or humid weather, and when pregnant (+300 ml) or breastfeeding (+700 ml). The calculator adds these and gives the amount to drink, plus an easy schedule through the day.
✏️ Worked examples
70 kg man, 30 min exercise, normal weather
You get| Water to drink a day | 2.2 litres |
| In glasses (250 ml) | 9 glasses |
| Total water incl. food | 2.8 litres (about 20% comes from food) |
| Extra for exercise | 0.35 L for 30 min |
| EFSA reference (total water) | 2.5 L a day for men |
2.2 litres (9 glasses).
60 kg woman, breastfeeding, hot weather
You get| Water to drink a day | 2.6 litres |
| In glasses (250 ml) | 11 glasses |
| Total water incl. food | 3.3 litres (about 20% comes from food) |
| Extra for exercise | none |
| EFSA reference (total water) | 2.0 L a day for women |
2.6 litres (11 glasses).
🧭 How to use this calculator
What you enter
- Weight (kg)
- Age (years)
- Sex
- Exercise a day (min)
- Weather
- Pregnant or breastfeeding?
What you get
- Water to drink a day
- In glasses (250 ml)
- Total water incl. food
- Extra for exercise
- EFSA reference (total water)
❓ Frequently asked questions
How much water should I drink a day?
Most adults need about 2–3 litres of drinks a day — 8 to 12 glasses — more in summer or when active. A 70 kg man doing 30 minutes of exercise needs about 2.2 litres of drinks.
Do tea, coffee and milk count?
Yes. All drinks count towards your fluid, including tea and coffee in moderate amounts. Water is best because it has no sugar or calories.
Can I drink too much water?
Very large amounts in a short time (many litres in a few hours) can dilute blood sodium. Spread drinks through the day. People with kidney or heart failure must follow their doctor's limit.