Water intake calculator
& bottle converter.
See published adult daily references, or convert an amount you already have into full bottles and a remainder. References are not a personal drinking target.
Choose your starting point
Use a published adult reference, or convert a volume you choose.
Enter 0.01–20 liters. This converts a volume you choose; it does not recommend how much to drink.
Check the amount and the allowed range.
About you
Age helps us show the right context, not a fixed age-based dose.
This tool uses references for adults 19 and older. It does not calculate an amount for children or teenagers. Read who the reference covers →
For healthy adults 19+. A population reference, not your personal requirement. Who is this for?
Exercise or heat? Optional guidance
This changes your guidance. It does not add a fixed amount to the reference.
Your bottle
Have a different bottle?
Enter 1–128 US fl oz. Leave blank to use a preset.
Your day,
in perspective.
Choose your age range and an adult reference. Exercise and heat guidance is optional.
About US fl oz from all beverages
An illustration of volume, not a drinking schedule.
Water, coffee, tea and other drinks count.
Not extra water to add to your usual drinks.
For your day
At 65 or older, age adds context rather than reducing this reference. See the guidance on individual needs before treating the amount as a daily goal.
Explore the guidance →The whole picture
Pregnancy, breastfeeding, illness, fluid restrictions, endurance exercise and extreme heat need different guidance. Read the limits →
Where do these numbers come from?
The U.S. National Academies report lists adult total-water references of 2.7 L for women and 3.7 L for men. Its accompanying beverage amounts are approximately 2.2 L and 3.0 L. Food provides the remaining 0.5 L and 0.7 L in that table; these are not measurements of your diet.
Reference mode converts those beverage amounts into US fluid ounces and your selected container size. Convert mode divides a volume you enter by your bottle capacity; it does not calculate a daily target. Your age range determines whether this adult reference applies. Your day changes the guidance beside it. Neither changes the published amount; we do not calculate a medical requirement from weight, age, heat or exercise.
Read the original report: Summary, Table S-2 ↗Try an example: How many bottles of water is 2 liters? Compare bottle sizes and print your conversion.
Good to know.
Easy to understand.
Does coffee count?
Yes. The reference includes water and other beverages, including coffee and tea. It is not an amount of plain water to add on top.
How does my profile change the result?
Age determines whether the adult reference applies. Activity changes the guidance, not the published amount. Weight is not requested because this tool does not use a weight-based formula. See the method.
What about exercise or losing weight?
Those are different questions. Read our guides to exercise and heat and water and weight loss.