Water Intake Calculator
See adult total-water reference values and learn what they include.
View an adult total-water reference
What this tool tells you
There is no one-size-fits-all water formula. This tool shows adult population Adequate Intake reference values for total water from drinks and food, not a personalized drinking target.
How the estimate works
The National Academies established Adequate Intakes of 3.7 L/day for men and 2.7 L/day for women aged 19 and older, with separate values for pregnancy and breastfeeding that this tool does not model. These are total-water values that include plain water, other beverages, and water in food. The calculator converts the chosen reference value to fluid ounces and approximate cups.
Important limitations
These are population reference values, not medical instructions, minimum requirements, or plain-water targets. Needs vary with heat, exercise, diet, pregnancy, breastfeeding, illness, and fluid restrictions. If you have a health condition affecting fluids, follow your clinician's advice.
Frequently asked questions
Does food count toward total water?
Yes. These reference values include water from food as well as beverages.
Should I drink the whole amount as plain water?
No. The displayed value is for total water from all sources, so it is not a plain-water goal.
Why isn't body weight used?
A simple weight-based formula cannot reliably capture all factors that determine personal fluid needs. This tool shows established reference values instead.
Learn more about hydration
These guides explain total water, what counts toward it, and why an adult reference value is not a personal drinking target.