Water Intake Calculator
Water intake calculator: how many ounces of water to drink per day based on your weight and exercise.
Editorial review: Farrow (pseudonym; identity and professional credentials are not disclosed). This page is for educational purposes, not professional advice.
Your inputs
Results update as you type. Nothing you enter leaves your device.
Results
- In cups (8 oz)
- 12.1
- In liters
- 2.87 L
Example with the starting values
These results use the calculator's initial inputs. Change the values above to calculate your own estimate.
Inputs
- Weight
- 170 lb
- Exercise per day
- 30 min
Results
- Daily water
- 97 oz
- In cups (8 oz)
- 12.1
- In liters
- 2.87 L
How does the Water Intake Calculator work?
Water intake is the total amount of water you drink in a day. A common rule of thumb is half an ounce of water per pound of body weight, plus 12 oz for every 30 minutes of exercise.
For example, a 170 lb person who exercises 30 minutes a day needs 170 × 0.5 + 12 = 97 oz, about 12 cups or 2.9 liters. Hot weather, illness, pregnancy and breastfeeding raise the need.
Frequently asked questions
How much water should I drink a day?
A common guide is half your body weight in ounces, so a 160 lb adult would aim for about 80 oz, or 10 cups. The National Academies suggest about 125 oz of total fluid for men and 91 oz for women.
How many ounces are in 8 glasses of water?
Eight 8-ounce glasses equal 64 oz, or about 1.9 liters. This 8x8 rule is easy to remember but is lower than many adults need.
Can you drink too much water?
Yes. Drinking more than your kidneys can clear, roughly 1 liter (34 oz) an hour, can cause hyponatremia, a dangerous drop in blood sodium. Spread intake across the day.
Does food count toward water intake?
Yes. About 20% of daily water typically comes from food, according to the National Academies.