Convert fluid ounce (us) to milliliters

mL = fl oz × 29.5735295625

The value is exact, because the US fluid ounce is defined as 1/128 of a US gallon, and the gallon is defined as exactly 231 cubic inches. For nutrition labels the US Food and Drug Administration rounds it to 30 mL, which is why a label may disagree with a precise conversion by a few percent.

The British imperial fluid ounce is 28.4131 mL, about 4% smaller than the American one. Oddly, the imperial pint is larger than the US pint — 20 imperial fluid ounces against 16 US ones — so the two systems disagree in opposite directions at different sizes. A recipe from a UK source should be converted with the imperial figure.

Fluid ounces also measure volume, not weight. Ounces on a kitchen scale are a different unit — see ounces to grams.

The limit for liquids in carry-on bags is usually quoted as 3.4 oz in the United States and 100 mL almost everywhere else. It is the same rule: 100 mL is 3.38 US fluid ounces, rounded to 3.4 on the sign. A container marked 3.5 fl oz (103.5 mL) is technically over, even if it is half empty — the limit applies to the size printed on the container.

• 1.5 fl oz (a US jigger / shot) = 44 mL
• 8 fl oz (one US cup) = 237 mL
• 12 fl oz (a soda can) = 355 mL
• 16 fl oz (a US pint) = 473 mL

The US fluid ounce is 1/128 of a US gallon, exactly 29.5735295625 mL (NIST Special Publication 811, the US guide to the SI lists it rounded, as 29.57353 mL). For nutrition labels the FDA rounds it: 21 CFR 101.9 says that for nutrition labeling, one fluid ounce means 30 mL. The British imperial fluid ounce is smaller, about 28.41 mL.