How much water should I drink?
Start with a general reference, then understand what it includes.
The U.S. National Academies lists total-water references of 2.7 liters per day for adult women and 3.7 liters for adult men. Those totals include food. The accompanying beverage amounts are approximately 2.2 and 3.0 liters, respectively—not that much plain water on top of your other drinks.
Source: Dietary Reference Intakes, Summary Table S-2. These are population references for adults 19 and older, not a minimum everyone must reach.
What counts toward the total?
Water and other beverages, including coffee and tea, contribute to the beverage amount. Food contributes to total water too. The table assigns 0.5 liters from food for women and 0.7 liters for men; these are reference values, not a measurement of your meals.
Does drinking less mean I am dehydrated?
Not automatically. An adequate-intake reference is not an individual diagnostic threshold. In Seal and colleagues’ study of 99 U.S. adults, some participants below the reference still met the study’s urine-concentration criterion. The study does not establish a personal daily minimum.
What if I exercise or spend time in the heat?
Your circumstances can change fluid needs. This page does not provide an exercise allowance or hourly target. Read the exercise and heat guide for the evidence and its limits.
When does this general reference not answer my question?
Children, pregnancy, breastfeeding, illness and prescribed fluid restrictions need different guidance. The calculator does not diagnose dehydration or replace individual clinical advice. See the scope and methodology.
How does that look in my bottle?
The calculator converts the beverage reference into your chosen container size. The count illustrates volume; it is not a drinking schedule or a record of what you have consumed.
Evidence reviewed September 7, 2026.