21 US fluid ounces to US cups
2.625 cup
21 fl oz = 2.625 cup.
US cups
2.625cup
21 fl oz = 2.625 cup
In short
How many US cups is 21 US fluid ounces?
21 fl oz = 2.625 cup. 1 US fluid ounce = 0.125000 US cups, so the working is 21 × 0.125000 = 2.625.
The working
The factor below is an exact definition rather than a measurement, so nothing is approximated in the arithmetic. The only rounding on this page happens where a number is displayed.
1 US fluid ounce = 0.125000 US cups 21 × 0.125000 = 2.625
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (cup) | Off by |
|---|---|---|
| Whole number | 3 | +0.37500 |
| 1 decimal | 2.6 | −0.02500 |
| 2 decimals | 2.63 | +0.00500 |
Round trip: take 2.625 cup back the other way and you land on 21.0000 fl oz — a drift of 0.0000 fl oz. That gap is the rounding, not the conversion.
Frequently asked questions
What is 21 US fluid ounces in US cups?
21 US fluid ounces is 2.625 US cups. 1 US fluid ounce = 0.125000 US cups, so the working is 21 × 0.125000 = 2.625.
How accurate is 2.625 cup?
Rounding to 2.625 cup and converting straight back gives 21.0000 fl oz, a drift of 0.0000 fl oz from the 21 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
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