Fluid Ounces to Milliliters

In the US customary system the gallon is exactly 231 cubic inches, and a fluid ounce is 1/128 of it. Because the inch has been exactly 2.54 cm since 1959, the US fluid ounce works out to exactly 29.5735295625 mL. American recipes, drink sizes, baby bottles and liquid medicine cups all use it, so anyone following US instructions with metric measuring jugs needs this conversion.

Common sizes to remember: a 12 fl oz soda can is 355 mL, a 16.9 fl oz water bottle is 500 mL, a 20 fl oz soda bottle is 591 mL and a 64 fl oz juice carton is 1.89 L. Coffee shop cups run from 8 fl oz (237 mL) to 20 fl oz (591 mL) and more.

Cocktail recipes from the US count in ounces. A standard jigger pours 1.5 fl oz, which is 44.4 mL, and its small side 0.75 fl oz, about 22 mL. In the UK and Ireland bars pour spirits in 25 mL or 35 mL measures instead, so a US recipe calling for 2 oz of gin is 59 mL, more than two UK singles.

Baby bottles are often marked in both units: 4 fl oz is 118 mL and 8 fl oz 237 mL, though some bottles round to 120 mL and 240 mL. For liquid medicine, follow the milliliter markings on the supplied syringe rather than converting from ounces.

A British recipe or older UK label may use the imperial fluid ounce, which is 28.41 mL. An imperial pint is 20 of those, 568 mL, while a US pint is 16 US fl oz, 473 mL. If a recipe is from the UK, Ireland or an older Australian cookbook, multiply by 28.41 rather than 29.57.

To convert back, use milliliters to fluid ounces. For cups and spoons, the cups to milliliters page covers kitchen measures.