Water Intake Calculator
See how much water adults need each day, from drinks and food, using the U.S. National Academies’ Adequate Intakes for women, men, pregnancy, and breastfeeding, in liters or fluid ounces. Calculates privately in your browser.
Total water a day (drinks + food)
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Show the math
These are the U.S. National Academies' Adequate Intakes for total water (2005):
women 2.7 L
men 3.7 L
pregnancy 3.0 L
breastfeeding 3.8 L a day
Total water counts everything, drinks and the water in food. In U.S. surveys about 80% came from drinks and about 20% from food, so the drinks line (2.2 L for women, 3.0 L for men) is the part most people drink. These figures fit generally healthy, moderately active adults. Hard exercise and heat add to them, sometimes a lot: distance runners often sweat about 0.7–1.0 L an hour in mild weather, so drink to replace what you lose. Let thirst and urine color guide you day to day.
What this does
A water intake calculator shows how much total water adults need each day, from drinks and food, using the U.S. National Academies’ Adequate Intakes (2005), and how much of that usually comes from drinks.
How it works
These Adequate Intakes are for adults 19 and over (19–50 for pregnancy and breastfeeding) and count all water, from drinks and from food. In U.S. surveys drinks supplied about 80% and food about 20%, so the tool also shows the drinks share: about 2.2 L for women, 3.0 L for men, 2.3 L in pregnancy, and 3.1 L while breastfeeding.
women 2.7 L
men 3.7 L
pregnancy 3.0 L
breastfeeding 3.8 L of total water a day
How to use it
- Choose woman, man, pregnant, or breastfeeding.
- Choose liters or US fluid ounces.
- Read your total water a day and the part from drinks.
- Add more for hard exercise or hot weather.
Understanding your result
The figures fit generally healthy, moderately active adults. Hard exercise and heat raise your needs, sometimes a lot (distance runners often sweat about 0.7–1.0 L an hour in mild weather), so drink to replace what you lose, and use thirst and urine color as everyday cues.
Example
A man needs about 3.7 L of total water a day, about 3.0 L (roughly 13 cups) of it from drinks and about 0.7 L from food; a woman needs about 2.7 L, with about 2.2 L (roughly 9 cups) from drinks.
Sources & methodology
- CDC, About Water and Healthier Drinks, Daily hydration guidance
Last updated .
Frequently asked questions
Where do the numbers come from?
From the U.S. National Academies’ Dietary Reference Intakes for water (2005). The Adequate Intake of total water is 2.7 L a day for women and 3.7 L for men aged 19 and over, 3.0 L in pregnancy, and 3.8 L while breastfeeding.
Does food count toward this?
Yes. The total includes the water in food, which supplied about 20% in U.S. surveys; drinks, including plain water, supplied about 80%. So a woman’s 2.7 L works out to about 2.2 L from drinks, and a man’s 3.7 L to about 3.0 L.
Why doesn’t it use my weight or exercise time?
The Adequate Intakes are set by sex and life stage, not body weight, and already fit moderately active adults. Sweat losses vary too much to add a fixed amount: in hard exercise or heat, drink to replace what you lose.
Do I need more in some situations?
Yes. Hard exercise, hot weather, high altitude, and illness can all raise your needs. Use thirst and urine color as everyday guides.
Is my data stored?
No. All calculations happen locally in your browser.
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