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Water bottle size calculator
Work out how many refills a day you need, which bottles fit your car cup holder and what each bottle costs per day. Defaults are set to a 64 oz day and a 24 oz bottle.
Refills per day and cost per day
Set your own target. The National Academies set total water intake references that include water from food, and your needs vary, so ask a doctor about yours. More calculators.
Will it fit my cup holder?
Measure across the opening, not the rim. Base widths are listing numbers, and car holders taper, so leave a little room.
| Bottle | Size | Base width |
|---|---|---|
| Owala FreeSip | 24 oz | 3.24 in |
| Hydro Flask Wide Mouth | 32 oz | 3.5 in |
| YETI Rambler 26 oz | 26 oz | 3.5 in |
| Takeya Actives | 32 oz | 3.74 in |
| Stanley IceFlow 2.0 | 30 oz | 3.76 in |
| CamelBak Chute Mag | 25 oz | Not listed |
| Nalgene Sustain 32 oz | 32 oz | Not listed |
| Thermos Funtainer | 12 oz | Not listed |
| Simple Modern Summit | 32 oz | Not listed |
| LifeStraw Go | 22 oz | 2.64 in |
Calculator questions
What size water bottle should I get?
A 24 oz bottle fits a bag pocket and needs about three refills for a 64 oz day. A 32 oz bottle needs two.
How many refills is 64 oz?
Three refills with a 24 oz bottle and two with a 32 oz bottle.
Does a 40 oz bottle fit a cup holder?
Rarely. Check the base width in the table and your own holder.
How is cost per day worked out?
Price divided by the days you keep the bottle. A $30 bottle kept three years costs about 3 cents a day, and a $100 special-edition color kept the same three years costs about 9 cents, which is the clearest way we know to see what a premium color really adds over the life of a bottle.
Why round refills up?
Nobody refills 2.7 times.