# US fluid ounces to US cups converter

> Convert US fluid ounces to US cups (oz to cups) with the exact factor, a conversion chart and worked steps.

Interactive version: https://www.calcopenly.com/conversion/ounces-to-cups
Subject: Unit converters

US fluid ounces are volume measures used on beverage packaging and measuring cups. They are different from ounces of mass and from imperial fluid ounces. Use the labelled US amount as the starting value, and do not infer an ingredient's weight from volume alone.

One US fluid ounce is exactly 0.125 US cups, so 12 fl oz is 1.5 cup. To convert oz to cups, multiply by 0.125; to convert back, multiply by 8.

The US fluid ounce is 1/128 of a US gallon, exactly 29.5735295625 mL. Because both units are defined exactly, the factor above is exact and the results here carry no conversion error.

## Inputs

- **US fluid ounces (fl oz)**

## Results

- US cups (cup) — main result
- Conversion
- 1 cup in US fluid ounces (fl oz)

## Formula

$$
\text{US cups} = \text{US fluid ounces} \times 0.125
$$

## Worked examples

### 12 fl oz to cup

- US fluid ounces (fl oz): 12 fl oz
- **US cups: 1.5 cup**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 8 fl oz to cup

- US fluid ounces (fl oz): 8 fl oz
- **US cups: 1 cup**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 32 fl oz to cup

- US fluid ounces (fl oz): 32 fl oz
- **US cups: 4 cup**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert oz to cups?

US fluid ounces are volume measures used on beverage packaging and measuring cups. They are different from ounces of mass and from imperial fluid ounces. Use the labelled US amount as the starting value, and do not infer an ingredient's weight from volume alone.

### How many US cups are in a US fluid ounce?

One US fluid ounce is exactly 0.125 US cups. The US fluid ounce is 1/128 of a US gallon, exactly 29.5735295625 mL.

### How do you convert oz to cups?

Multiply the number of US fluid ounces by 0.125. For example, 12 fl oz × 0.125 = 1.5 cup. To go the other way, divide by 0.125.

### Is a cup 240 mL or 236.6 mL?

Both are in use. The US customary cup in recipes is 236.588 mL. US nutrition labels use a rounded "legal cup" of 240 mL (21 CFR 101.9), and the metric cup used in Australia, New Zealand and Canada is 250 mL.

### How accurate is the US fluid ounces to US cups converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “12 fl oz to cup” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C: General tables of units of measurement](https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/handbook-44)
- [BIPM, The International System of Units (SI Brochure), 9th edition](https://www.bipm.org/en/publications/si-brochure)