How much water do you need?
The National Academies set an adequate intake of total water, from all drinks and food, of about 3.7 liters a day for men and 2.7 liters for women. Food supplies roughly 20%, so drinks need to cover about 3 liters (101 oz) for men and 2.2 liters (73 oz) for women.
Example: a man who exercises for 30 minutes on a normal day should drink about 112 oz (3.3 liters, 14 cups).
What counts
- All drinks count, including milk, tea and coffee. Caffeine's mild diuretic effect doesn't cancel out the water.
- Water-rich foods like fruit, vegetables and soup add to your intake.
- The popular "half your body weight in ounces" rule isn't from a scientific guideline, but lands in a similar range for many people.
- Drinking far more than your kidneys can clear, several liters in a short time, can be dangerous. People with heart or kidney conditions should follow their doctor's advice.
Planning a workout? Estimate the effort with the calories burned calculator.
Frequently asked questions
How much water should I drink a day?
About 101 oz (3 liters) of fluids for men and 73 oz (2.2 liters) for women, plus extra for exercise and heat, with the rest of your water coming from food.
Is 8 glasses of water a day enough?
Eight 8 oz glasses is 64 oz, slightly below the guideline for most adults once you count only drinks, but food and other beverages often make up the difference.
Does coffee count toward water intake?
Yes. Coffee and tea are mostly water, and studies show moderate amounts hydrate about as well as water.
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