How Much Water Should You Drink?
The US National Academies recommends about 3.7 liters (125 oz) of total water per day for men and 2.7 liters (91 oz) for women — but that includes water from food. Actual drinking water needs vary widely based on body weight, activity, climate, and health.
Our Formula
We base our estimate on the widely-used guideline of 0.5–1 oz of water per pound of body weight, adjusted for exercise intensity and climate. For example, a 165 lb adult exercising moderately in a temperate climate needs about 100 oz of water daily — roughly 12–13 cups.
Factors That Increase Water Needs
- Exercise — add 12–24 oz per hour of activity
- Hot or humid weather — add 10–20%
- High altitude — above 8,000 ft increases need
- Pregnancy or breastfeeding
- Illness with fever, vomiting, or diarrhea
- High-protein or high-fiber diets
Signs You're Dehydrated
- Dark yellow urine
- Dry mouth and lips
- Fatigue and dizziness
- Headache
- Decreased urine output
Can You Drink Too Much Water?
Yes — hyponatremia (water intoxication) is rare but dangerous. Endurance athletes are most at risk. Don't exceed 1 liter per hour, and balance water with electrolytes during long exercise.