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Water intake calculator: how much water you need a day

A simple guide is about 30 ml of water per kg of body weight a day, plus about 0.5 to 1 litre per hour of exercise. For a 72 kg adult, that is about 2.2 litres. Official references: 2.0 L a day for women and 2.5 L for men, food included.

Your water

Weightlb
Exercise a daymin
Hot weather or a lot of sweating
Water a day83 fl ozAbout 10 glasses of 250 ml

Food covers about 20% of this. Reference intakes (EFSA) for all water, food included: 2.0 L for women, 2.5 L for men.

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30 ml per kg, plus about 0.6 L per hour of exercise and 0.5 L in hot weather. An estimate, not medical advice.

How much water do you need?

Body weightWater a day (no exercise)With 1 hour of exercise
55 kg (121 lb)1.65 L2.25 L
65 kg (143 lb)1.95 L2.55 L
75 kg (165 lb)2.25 L2.85 L
85 kg (187 lb)2.55 L3.15 L
95 kg (209 lb)2.85 L3.45 L

These are guides, not rules. Your thirst is a good signal for most healthy adults, and pale yellow urine is a simple check that you drink enough. Tea, coffee, milk and the water in fruit, vegetables and soups all count.

Water and weight loss

  • Before meals: in one trial, adults who drank 500 ml of water before meals lost more weight over 12 weeks than those who did not.
  • Instead of sugary drinks: swapping one soda or juice a day for water saves 100 to 150 kcal.
  • Water weight is not fat: salt, carbs and hormones move the scale by a kilo or more in a day. Look at your weekly average.

When you need more

  • Exercise: about 0.4 to 0.8 L per hour, more in the heat.
  • Hot weather, fever or illness with vomiting or diarrhoea.
  • Pregnancy and breastfeeding: about 0.3 to 0.7 L more a day.
  • High-protein diets and GLP-1 medication, when appetite is low.

More tools: your protein for the day, and the calories burned by your workout. On GLP-1? Read what to eat on Ozempic.

Questions about water

Is 2 litres of water a day enough?

For many adults, yes. The European reference is 2.0 L of total water for women and 2.5 L for men, including the water in food, which is about 20%.

Does coffee count toward water intake?

Yes. Moderate coffee and tea hydrate almost as well as water. Alcohol is the exception.

Does drinking water help you lose weight?

A little. Water before meals can make you eat less, and replacing sugary drinks with water saves calories. It does not burn fat on its own.

Can you drink too much water?

Yes, but it is rare: several litres in a few hours can lower blood sodium. Spread your water over the day and follow your thirst.

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Read next

Sources

  1. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on dietary reference values for water. EFSA Journal, 2010.
  2. American College of Sports Medicine. Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 2007.
  3. Dennis EA, et al. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity, 2010.

This calculator gives general estimates, not medical advice. If you have heart or kidney disease, or your doctor limits your fluids, follow their advice.

By the Enough team ·