Water Intake Calculator
Calculate your recommended daily water intake based on body weight, exercise, and climate. Results in liters, ounces, cups, and bottles.
Your details
Enter your weight to see your recommended daily water intake.
Informational only, not medical advice. Individual needs vary with health, medications, and pregnancy.
Frequently Asked Questions about the Water Intake Calculator
How is daily water intake calculated?
The base is 35 ml per kg of body weight (about 0.5 oz per lb). The calculator adds 500 ml per hour of exercise and another 500 ml if you live in a hot climate. Result shows ml, liters, fl oz, cups, and 16 oz bottles.
Where does the 8 glasses a day rule come from?
It is folklore, not science. The U.S. National Academies set adequate intake at about 3.7 liters per day for men and 2.7 for women, including water from food. Body weight and activity scale needs more accurately than a fixed number.
Does coffee or tea count toward hydration?
Yes. The mild diuretic effect of caffeine is offset by the fluid in the drink, so coffee, tea, and most non-alcoholic beverages count. Alcohol does dehydrate you in larger doses, so do not count beer or wine as hydration.
What are the signs I am not drinking enough water?
Dark yellow urine, infrequent urination (less than 4 times a day), dry mouth, headaches, fatigue, and cravings that feel like hunger. Pale straw-colored urine is the simplest sign that intake is adequate.
Can you drink too much water?
Yes. Hyponatremia happens when sodium is diluted by excessive water, usually 4 to 6 liters in a few hours during endurance events. Symptoms include nausea, confusion, and seizures. Spread intake across the day and use electrolytes during long exercise.
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