Free tool
Water intake & bottle refill calculator
It estimates how much you should drink each day, based on National Academies guidelines plus exercise. Then it tells you how many times to refill your bottle and when to finish each one.
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Drink per day (all beverages)
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From your bottle
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Fills per day
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Your refill schedule
Fills per day by bottle size
| Bottle | Fills/day |
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Bottle suggestion
How is the daily target calculated?
Baseline. The National Academies' adequate intake for water from beverages for adults 19+: 3.0 L (about 101 oz) for men, 2.2 L (74 oz) for women, 2.3 L (78 oz) in pregnancy and 3.1 L (105 oz) when breastfeeding (National Academies, Table S-2). Total water, including food, is higher (3.7 L and 2.7 L). Mayo Clinic notes that about 20% comes from food (Mayo Clinic).
Exercise. We add 7 oz per 20 minutes of exercise, the low end of the American Council on Exercise's 7–10 oz every 10–20 minutes (ACE).
Other drinks. Coffee, tea and milk count toward your fluids (Mayo Clinic), so we subtract them from what your bottle needs to cover.
What doesn't the calculator account for?
Hot or humid weather, high altitude, illness, kidney or heart conditions, and children's needs. Mayo Clinic says hot weather and altitude raise fluid needs (Mayo Clinic). This is a general estimate, not medical advice. If you have a health condition, ask your clinician how much to drink.
Can I link to or embed this calculator?
Yes. Bloggers, coaches and teachers are welcome to link to this page. Results are saved in the URL, so you can share a specific calculation.
Frequently asked questions
How much water should I drink a day?
The National Academies' adequate intake from beverages is about 101 oz (3.0 L) for adult men and 74 oz (2.2 L) for adult women, plus more when you exercise or it's hot.
How many 40 oz bottles is that?
About 2.5 a day for men and 1.9 for women, before exercise. See our refill guide for the full table.
Does coffee count toward water intake?
Yes. Mayo Clinic says coffee, tea and milk count toward daily fluids.
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