Water intake at 80 lb
How much water is enough? Use the form for your own numbers, or read the example for 80 lb with 30 minutes of exercise.
How it works
The estimate starts at 35 milliliters per kilogram of body weight. Each 30 minutes of exercise adds 350 milliliters. The page shows the total in milliliters, liters and ounces. This page converts 80 lb to 36.29 kg first, with 30 minutes of exercise.
Worked example
Convert first: 80 lb is 36.29 kg. Then 36.29 × 35 = 1270.15 ml. Exercise adds 350 × 30 divided by 30 = 350 ml. 1270.15 + 350 = 1620.15 ml. That is 1.62 liters, 54.8 ounces or 6.8 cups.
Common questions
Does food count toward the total?
Food contains water. Treat the result as a goal for your total fluid across the day and not a quota for drinks alone. At 80 lb with 30 minutes of exercise, treat 1.62 liters as a goal for the day, not a quota for one sitting.
What if I exercise more or less than this?
Change the exercise minutes. Each 30 minutes adds 350 milliliters. At 30 minutes the page adds 350 ml. An extra 30 minutes would bring the total to 1970.15 ml.
Is 35 milliliters per kilogram right for everyone?
No. It is a common starting estimate. Heat, illness, pregnancy and some health conditions change needs. For 80 lb the starting figure is 1270.15 ml before exercise, and 1620.15 ml with 30 minutes of exercise.
Can I drink too much water?
Yes, though it is uncommon. Drinking far more than you need in a short time can dilute the salts in your blood. Spread your intake through the day. At 80 lb with 30 minutes of exercise, spread over 16 waking hours, 1.62 liters is about 101 ml an hour.
How many ounces or cups is that?
A US fluid ounce is 29.5735 milliliters and a cup is 8 ounces. At 80 lb with 30 minutes of exercise, 1620.15 ml is 54.8 ounces or 6.8 cups.