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Water Intake Calculator

Enter your sex and weight, then select whether you’ll be working out or in hot weather. The calculator will show how much to drink throughout the day—in liters and glasses.

Sex
Weather
Pregnancy and breastfeeding

Enter your details and your results will appear here.

How do we calculate how much water to drink?

We start with the European Food Safety Authority (EFSA) guidelines: 2 l of water a day for women and 2.5 l for men. This includes water from all sources—drinks and food.

  1. Baseline—the EFSA guideline or 30 ml per kilogram of body weight, if that’s higher. Someone weighing 90 kg needs more water than someone weighing 55 kg.
  2. Water from food—about 20% of your water comes from soup, vegetables, fruit, and other foods. You need to drink the rest, or about 80%.
  3. Additional amounts—workouts: 0.6 l per hour, hot weather: 0.5 l, pregnancy: 0.3 l, breastfeeding: 0.7 l.

For example, a man weighing 90 kg who works out for an hour a day: baseline 2.7 l, of which about 2.2 l comes from drinks, plus 0.6 l for the workout—about 2.8 l in total, or about 11 glasses.

How much water to drink each day: chart

How much to drink on a typical day, without a workout or hot weather (from drinks, excluding water from food):

Weight Female Male
50 kg about 1.6 l (6 glasses) about 2 l (8 glasses)
60 kg about 1.6 l (6 glasses) about 2 l (8 glasses)
70 kg about 1.7 l (7 glasses) about 2 l (8 glasses)
80 kg about 1.9 l (8 glasses) about 2 l (8 glasses)
90 kg about 2.2 l (9 glasses) about 2.2 l (9 glasses)
100 kg about 2.4 l (10 glasses) about 2.4 l (10 glasses)

One glass is 250 ml. Read more about guidelines and what counts toward your fluid intake in our article How Much Water Should You Drink Each Day?

When do you need more water?

  • in hot weather or a heated, dry room—you lose more water through sweat and breathing,
  • during exercise—especially if it’s prolonged or in high temperatures,
  • when you eat a diet high in protein and fiber—fiber needs water to work properly,
  • after drinking alcohol—alcohol increases urine production,
  • with a fever, vomiting, or diarrhea—your body loses a lot of water. Consider consulting a doctor if a child or older adult has these symptoms, or if they last a long time.

Water and weight loss

Water has no calories, so swapping sweetened drinks for water is one of the simplest ways to cut your daily calorie intake. A can of cola has about 140 kcal—one a day for a month adds up to more than 4000 kcal.

For some people, having a glass of water before a meal helps them eat a little less. Drinking water itself does not “burn fat.” What matters is your calorie balance—you can check it with our daily calorie needs calculator.

How to drink more water

  • Keep a bottle or pitcher somewhere visible, like on your desk or kitchen counter.
  • Have a glass of water with each meal and one as soon as you wake up.
  • Add some flavor: a slice of lemon, a few mint leaves, or a handful of fruit.
  • Track how much you drink—after a few days, you’ll see whether you usually drink enough.

FAQs

How much water should women and men drink each day?
According to the European Food Safety Authority (EFSA), women need about 2 l of water a day, and men about 2.5 l—including water from food. That works out to roughly 1.6 l and 2 l from drinks. You may need more if you weigh more, work out, or spend time in hot weather.
Do coffee and tea count?
Yes. Coffee and tea consumed in typical amounts hydrate you similarly to water. Milk, soup, and juice count too—but juice and sweetened drinks contain a lot of sugar, so it’s best to treat them as extras.
How much water should I drink when I work out?
You usually need an extra 0.5-0.75 l for each hour of exercise—the calculator adds 0.6 l. You may need more if you sweat heavily, exercise in hot weather, or work out for a long time. Sometimes you may also need electrolytes.
Can you drink too much water?
Yes, though it’s rare. Drinking several liters in a short time can dilute the sodium in your blood. It’s safer to drink regularly throughout the day than to try to catch up by drinking a lot at once.
How much water should I drink during pregnancy and breastfeeding?
According to EFSA, you need about 0.3 l more water a day during pregnancy and about 0.7 l more while breastfeeding than usual. The calculator adds these amounts to your result.
How can I tell if I’m drinking enough?
Urine color is the simplest clue: pale straw-colored urine usually means you’re well hydrated, while dark urine suggests you may need a drink. Thirst can be a clue too, but it tends to become less noticeable with age. Older adults should drink regularly rather than waiting until they feel thirsty.

This calculator is for informational purposes only and does not replace advice from a doctor or dietitian. The calculations happen in your browser—we don’t send the data you enter anywhere. We only save it in this tab for the duration of your visit, so it can be filled in automatically in other calculators. Formulas and sources.

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