Cups to Fluid ounces

About Cups and Fluid ounces

Cups (cup): The US cup is exactly 236.588 mL, or 8 US fluid ounces; the metric cup (used in Australia and some metric cookbooks) is 250 mL; the UK imperial cup is 284 mL. Common uses: American cooking and baking — the dominant volumetric unit for ingredient measurement in US recipes; mostly absent from professional and metric-country recipes which prefer weight.

Fluid ounces (fl oz): 1/128 of a US gallon, or 29.5735 mL; the UK imperial fluid ounce is slightly different at 28.4131 mL, a remnant of pre-metric British measurement. Common uses: US beverage container sizes (a 12-oz soda can), US liquid recipe measurements, and UK pub measures for spirits (where a 'single' is 25 or 35 mL but historically tracked from imperial fl oz).

How the conversion works

Volume conversions use US customary measure (the cup, fluid ounce, and gallon are US definitions, not imperial). 1 US cup = 236.588 mL, 1 US gallon = 3.785411784 L.

The exact relationship is fluid ounces = cups × 8, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.

When this conversion matters

Converting between cups and fluid ounces comes up wherever volume measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.