Water intake calculator: how much water to drink a day
Choose female or male, how much you train and whether it's hot: we'll show you how many ounces, cups and liters of water to drink a day, with the EFSA reference intakes and what you sweat when you train. The chart is further down.
It's a reference for healthy adults, not medical advice. If you have kidney or heart disease or you've been told to limit fluids, follow your doctor. During pregnancy EFSA adds 300 ml of total water a day, and 700 ml while breastfeeding. Drinking much more than you sweat doesn't help: during exercise it can lower the sodium in your blood (hyponatremia).
Make it part of your day. In Mobbe you add each glass with one tap and see your water next to your meals, with PRO.
How much water to drink a day by training time
Fluid ounces a day between water and other drinks, on top of what food provides. In hot weather, each hour of training adds 27 oz instead of 17 oz.
| Training | Female | Male | Female, hot | Male, hot |
|---|---|---|---|---|
| 0 min | 54 oz | 68 oz | 54 oz | 68 oz |
| 30 min | 64 oz | 78 oz | 68 oz | 81 oz |
| 45 min | 68 oz | 81 oz | 74 oz | 88 oz |
| 60 min | 71 oz | 85 oz | 81 oz | 95 oz |
| 90 min | 81 oz | 95 oz | 95 oz | 108 oz |
| 120 min | 88 oz | 101 oz | 108 oz | 122 oz |
How water intake is calculated
The total water reference, what food provides and what you sweat when you train, with the worked example.
- Step 1
The total water reference
EFSA sets 2.0 liters a day for women and 2.5 liters for men (68 oz and 85 oz), counting drinks and food, at moderate temperatures and activity. The US reference is higher (2.7 and 3.7 liters) because it comes from what people drink, and it notes that for a healthy person drinking less may not add any risk. We use the European one.
total water = 2.0 L (women) or 2.5 L (men)EFSA, 2010; IOM, 2005. - Step 2
What food provides
About 20% of your water comes with food and the rest with drinks. That leaves 2.0 liters (68 oz) to drink for a man and 1.6 liters (54 oz) for a woman.
drinks = total water × 0.8IOM, 2005; EFSA, 2010. - Step 3
What you sweat when you train
During exercise people usually sweat 0.5 to 2 liters an hour. We add the low end, 0.5 liters (17 oz) an hour, and 0.8 liters (27 oz) in the heat: in female runners, sweat went from about 0.7 liters an hour in mild weather to 1.1 in warm weather. A man who trains 1 hour: 68 oz + 17 oz = 85 oz, about 11 cups.
training = 0.5 L (0.8 in the heat) × hoursACSM, 2007; IOM, 2005. - Step 4
Your real number
How much you sweat varies a lot from person to person. Weigh yourself before and after training: each kilo (2.2 lb) you lose is about 1 liter (34 oz). Don't drink more than you lost: drinking too much is the main cause of exercise-associated hyponatremia.
ACSM, 2007.
Sources
- EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). Scientific Opinion on Dietary reference values for water. EFSA Journal. 2010;8(3):1459. doi:10.2903/j.efsa.2010.1459
- Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: The National Academies Press; 2005. doi:10.17226/10925
- American College of Sports Medicine; Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-390. doi:10.1249/mss.0b013e31802ca597
Frequently asked questions
How much water should I drink a day?
About 54 oz (1.6 liters) of water and other drinks for a woman and about 68 oz (2.0 liters) for a man. With what food provides, that's 2.0 and 2.5 liters. If you train, add 17 oz an hour, or 27 oz in the heat.
How many ounces of water should I drink a day?
About 54 oz if you're a woman and 68 oz if you're a man, between water and other drinks, plus about 17 oz for every hour you train.
How many glasses of water should I drink a day?
About 7 cups of 8 oz for a woman and 8 for a man on a day without training. Coffee, tea and other drinks count too.
How much water should a woman drink a day?
About 54 oz (1.6 liters) of drinks, out of 2.0 liters of total water a day. Add about 17 oz for every hour of training.
How much water should I drink based on my weight?
The EFSA and US reference intakes aren't set per pound or kilo: they're set by sex and age. What changes your needs the most is how much you sweat, and you measure that by weighing yourself before and after training.
How much water should I drink to lose weight?
The same as to maintain your weight: no amount of water makes you lose weight by itself. Water has no calories, so swapping soda or juice for water does help you eat fewer calories.
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Mobbe builds your plan with these numbers
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