How to track water with your reusable bottle
Short answer: Find out how much your bottle actually holds, then log each refill you finish, or the fraction you drank (¾, ½ or ¼). That's it. Counting bottles is easier and more accurate than counting sips, and it takes one tap if you save the bottle in a tracker like Dropkin.
Updated 2026-10-14 by the Dropkin team.
Step 1: Find your bottle's real capacity
Look on the base or side, check the product listing, or measure it once: fill it with water and pour it into a measuring jug. Many bottles are sold by a rounded number but hold a little more when filled to the brim. Use the amount you normally fill to, not the brim, because that's what you drink.
If the capacity is in ounces, check which kind. A US fluid ounce is about 29.57 mL; an imperial (UK) fluid ounce is about 28.41 mL. Our bottle size converter does the maths for you.
Open the bottle size converter
Step 2: Decide what counts as one log
- Finished a full bottle: log one bottle.
- Finished most of it before refilling: log ¾.
- Drank half on the way to work: log ½.
- A few sips: skip it or log ¼. Small sips rarely change the picture.
Step 3: Log at a natural moment
The easiest moment to log is the refill. When you're at the tap anyway, that's the cue. Logging when you finish the bottle (not every time you sip) keeps tracking to a handful of taps a day.
Common bottle-tracking mistakes
- Using the label size when you never fill it to the top.
- Mixing US and imperial ounces.
- Logging the refill instead of what you drank, then forgetting to subtract what you poured away.
- Estimating every sip. It's tiring, and tiring habits don't last.
Doing it in one tap with Dropkin
Save the bottle once in My Vessels with its name and capacity and pin it. The big button on the Today screen logs the whole bottle, and visible ½ and ¼ buttons sit right next to it. You can log the same bottle from a Home Screen widget, Control Center, Siri or Apple Watch. Dropkin records what you tell it you drank; it can't measure what's left in a real bottle.
Sources
General information, not medical advice.
Is it better to count bottles or glasses?
Whichever you actually use. Counting the container you refill most is usually the least effort, which makes it easier to keep going.
How do I log half a bottle?
Log ½ of the bottle's capacity. In Dropkin there's a visible ½ button next to your pinned bottle, and you can also hold the main button.
Does Dropkin know how much water is left in my bottle?
No. It records the amount you log. Your phone can't measure a physical bottle.