Water intake at 120 lb
How much water is enough? Use the form for your own numbers, or read the example for 120 lb with 30 minutes of exercise.
How it works
Start with 35 milliliters for each kilogram you weigh. Add 350 milliliters for every 30 minutes you exercise. Divide milliliters by 29.5735 to get fluid ounces. At 120 lb with 30 minutes of exercise, the body weight part of the target is 1905.05 milliliters.
Worked example
Say a person weighs 120 lb with 30 minutes of exercise. That is 54.43 kg. The body weight part is 54.43 × 35 = 1905.05 ml. Exercise adds 350 × 30 divided by 30 = 350 ml. Together that is 2255.05 ml, which is 2.26 liters or 76.3 ounces. In cups that is 9.5.
Common questions
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 2605.05 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 120 lb the starting figure is 1905.05 ml before exercise, and 2255.05 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 120 lb with 30 minutes of exercise, spread over 16 waking hours, 2.26 liters is about 141 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 120 lb with 30 minutes of exercise, 2255.05 ml is 76.3 ounces or 9.5 cups.
Do coffee and tea count toward my water?
Most drinks count toward your fluid total, though plain water is the simplest choice. At 120 lb with 30 minutes of exercise, 2.26 liters a day is about 10 cups spread across the day.