How this water intake calculator works
This calculator uses the adequate intake for water set by the U.S. National Academies. It is based on sex, because that is how the guideline is written for healthy adults.
- Men: 3.7 liters (125 fl oz) of total water a day
- Women: 2.7 liters (91 fl oz) of total water a day
"Total water" means water from both food and drinks. About 20% usually comes from food. So we show 80% of the total as your drinks target. That works out to about 3.0 liters (101 fl oz, or about 12.7 cups) for men and 2.2 liters (74 fl oz, or about 9.3 cups) for women.
We also show the lower numbers from the European Food Safety Authority (EFSA): 2.5 liters (85 fl oz) for men and 2.0 liters (68 fl oz) for women, again from food and drinks.
What your result means
Think of your result as a daily guide, not a hard target. These numbers come from how much healthy people tend to drink. Most people can meet their needs by drinking with meals and when they feel thirsty.
You will likely need more water if you:
- Exercise or sweat a lot
- Spend time in hot or humid weather
- Are pregnant or breastfeeding
If you are pregnant, breastfeeding, or have kidney or heart problems, talk to your doctor or a registered dietitian about how much fluid is right for you.
Tips for drinking enough
- Keep a water bottle where you can see it.
- Have a glass of water with each meal.
- Eat water-rich foods like fruit, vegetables, and soup.
- Check your urine. Pale yellow usually means you are drinking enough.
Water and exercise
The American College of Sports Medicine says the goal during exercise is to avoid losing more than 2% of your body weight from sweat. Needs vary a lot from person to person. Weigh yourself before and after a workout to see how much you lost. Curious how hard your workout was? Try our calories burned calculator.
For more detail on daily needs, read our guide on how much water you should drink a day. Protein and fiber matter too, so check your protein target next.