CyanSunSizes
How Many ml Is a 12 oz Paper Cup?
A 12 oz paper cup is 355 ml by name. Measured to the brim, the same cup holds about 490 ml. The difference is not a mistake — it is headspace, and it decides how much you actually serve.
The short answer
12 US fluid ounces = 355 ml. That is the trade size printed on the carton. A standard 12 oz cup (90 mm rim, 60 mm base, 110 mm high) measures about 490 ml when filled to the rim.
A café fills to a line 10–20 mm below the rim, so the drink is closer to 400 ml. Ice, foam and a lid take up the rest.
Why the gap exists
| Measure | Volume | What it means |
|---|---|---|
| Trade size | 355 ml | The name on the carton |
| Brimful | 490 ml | Geometry of the cup |
| Safe fill | ~400 ml | Line below the rim |
| With ice | 300–350 ml drink | Ice displaces liquid |
Cup sizes came from US food service, where the ounce number was a serving convention, not a laboratory volume. Two factories can make a “12 oz” cup with slightly different dimensions and both be right.
Frequently Asked Questions
Is 12 oz the same as 355 ml?
By name, yes. The cup itself holds more when filled to the rim.
How much coffee goes in a 12 oz cup?
About 350–400 ml including milk, leaving room for the lid.
Why does my 12 oz cup look bigger than another 12 oz cup?
Different rim, base or height. Compare dimensions, not the ounce label.
Need the numbers for your own cup?
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