Calculate Your Daily Water Intake
Enter your body weight, activity level, and climate to get your personalized daily water target.
Water Intake Guidelines
Base intake: 30-35 ml per kg body weight (0.5-0.6 oz per lb)
Add for activity: +500-1,000 ml (17-34 oz) for moderate exercise, +1,000-1,500 ml (34-50 oz) for intense exercise
Add for climate: +500-1,000 ml (17-34 oz) in hot or dry climates
Total water intake includes water from beverages (water, tea, coffee, milk) and foods (fruits, vegetables, soups). About 20% of daily water intake comes from food.
Signs of Dehydration
- Dark yellow urine (healthy urine is pale yellow)
- Thirst
- Dry mouth and lips
- Fatigue
- Dizziness
- Decreased urine output
References
Frequently asked questions
How much water should I drink per day?
The National Academies recommend about 3.7 liters (125 oz) per day for men and 2.7 liters (91 oz) for women from all beverages and foods. A simple guideline is 30-35 ml per kg body weight (0.5-0.6 oz per lb). Active individuals and those in hot climates need more.
Does the "8 glasses a day" rule work?
The "8x8 rule" (eight 8-oz glasses = 64 oz or 1.9 liters) is a rough guideline. Actual needs vary by body weight, activity level, climate, and diet. Larger people and active individuals need more water.
Can you drink too much water?
Yes. Hyponatremia (low blood sodium) can occur from excessive water intake in a short period, especially during endurance exercise. Drink to thirst and monitor urine color (pale yellow = hydrated).
How to use the number
The result is a daily fluid target for the weight, activity, and climate you entered. It is a planning figure, not a medical prescription. Spread it through the day. Thirst and pale-yellow urine are the practical checks. Very dark urine is a reason to drink. Clear urine all day can mean you are ahead of thirst.
Food counts. Soups, fruit, and vegetables contribute water, which is why a total from beverages alone is not the whole story. The page already notes that a share of daily water comes from food. Coffee and tea count as fluid for most people. Alcohol does not help the same way. If you are doing long training in heat, the calculator's add-on for activity is a prompt to plan bottles, not a guarantee.
Do not force a huge volume in a short time. Low blood sodium from overdrinking is a known risk in long endurance events. Drink with the session, and include sodium if the session is long enough that your clinician or coach already told you to. This page does not set that protocol.
Water does not replace a calorie target. If the goal is weight change, set that on the calorie calculator and use steps to calories only as an activity estimate. The web calculators are free.