# US cups to US fluid ounces converter

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

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

A recipe written in US cups may need conversion for a graduated jug or a set of measuring spoons. Fractions such as a quarter or three quarters of a cup are valid inputs. This is a US customary cup; a metric cup uses a different capacity.

One US cup is exactly 8 US fluid ounces, so 2 cup is 16 fl oz. To convert cups to oz, multiply by 8; to convert back, multiply by 0.125.

The US customary cup is 8 US fluid ounces, exactly 236.5882365 mL. Because both units are defined exactly, the factor above is exact and the results here carry no conversion error.

## Inputs

- **US cups (cup)**

## Results

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

## Formula

$$
\text{US fluid ounces} = \text{US cups} \times 8
$$

## Worked examples

### 2 cup to fl oz

- US cups (cup): 2 cup
- **US fluid ounces: 16 fl oz**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 1 cup to fl oz

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

### 6 cup to fl oz

- US cups (cup): 6 cup
- **US fluid ounces: 48 fl oz**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert cups to oz?

A recipe written in US cups may need conversion for a graduated jug or a set of measuring spoons. Fractions such as a quarter or three quarters of a cup are valid inputs. This is a US customary cup; a metric cup uses a different capacity.

### How many US fluid ounces are in a US cup?

One US cup is exactly 8 US fluid ounces. The US customary cup is 8 US fluid ounces, exactly 236.5882365 mL.

### How do you convert cups to oz?

Multiply the number of US cups by 8. For example, 2 cup × 8 = 16 fl oz. To go the other way, divide by 8.

### 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 cups to US fluid ounces 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, “2 cup to fl oz” 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)