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US cups to US fluid ounces

Multiply US cups by 8 to get US fluid ounces.

1 cup = 8 fl ozNIST HB 44
cup
12fl oz

1.5 cup = 12 fl oz

How to convert US cups to US fluid ounces

The US fluid ounce is a US fluid ounce, one 128th of a gallon (29.5735295625 millilitres). The US cup is a US customary cup, one sixteenth of a gallon (236.5882365 millilitres).

Worked example — 1.5 cup: 1.5 × 8 = 12 fl oz.

US cups to US fluid ounces table

Common conversions.
US cupsUS fluid ounces
0.25 cup2 fl oz
0.5 cup4 fl oz
0.75 cup6 fl oz
1 cup8 fl oz
1.5 cup12 fl oz
2 cup16 fl oz
3 cup24 fl oz
4 cup32 fl oz
8 cup64 fl oz

Reverse and related

About US cups and US fluid ounces

US cup (cup)

1 cup = 8 fl oz

Definition. A US customary cup, one sixteenth of a gallon (236.5882365 millilitres)

History and origin

The US customary cup was standardised as a cooking measure at one sixteenth of a gallon, about 237 millilitres. It became popular through American recipe books in the nineteenth and twentieth centuries.

Current use

The cup is the dominant volume measure in US home cooking and baking; metric recipes usually give millilitres or grams instead.

Source: NIST Handbook 44, Appendix C §2 (U.S. Customary Units) and §5 (Tables of Equivalents)

US fluid ounce (fl oz)

1 fl oz = 0.125 cup

Definition. A US fluid ounce, one 128th of a gallon (29.5735295625 millilitres)

History and origin

The fluid ounce began as the volume of one ounce of wine or water and later diverged between the US and imperial systems. The US fluid ounce is one 128th of a gallon, about 29.6 millilitres.

Current use

Fluid ounces measure drink sizes and recipe liquids in the United States; the imperial fluid ounce used elsewhere is slightly smaller.

Source: NIST Handbook 44, Appendix C §2 (U.S. Customary Units) and §5 (Tables of Equivalents)

Where people use this

US cups: recipes, baking. US fluid ounces: drink sizes, recipe liquids. 1 US cup is 8 fluid ounces.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 fl oz = 0.125 cup, so 1 cup = 1 ÷ 0.125 = 8 fl oz.

Every value is carried to full double precision; the display is rounded.

Both units are defined in NIST Handbook 44, Appendix C §2 (U.S. Customary Units) and §5 (Tables of Equivalents).

Questions people ask

How many fluid ounces in a cup?

One US cup is exactly 8 fluid ounces.

How many fl oz is 2 cups?

2 US cups is 16 fluid ounces.

How many fl oz is half a cup?

Half a US cup is 4 fluid ounces.

All US cup conversions