US fluid ounces to US cups converter

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

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.

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.

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).

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.