Fluid Ounces to Millilitres

How to use Fluid Ounces to ML Converter

1. 1
   Check which ounce. American recipes use the US fluid ounce; older British ones use imperial.
2. 2
   Enter the value. Both conversions appear, so a mislabelled source is obvious.

About converting fluid ounces to millilitres

Converting fluid ounces into millilitres is the direction most people need, because metric kitchens are the ones following American recipes rather than the other way round. The multiplier is 29.5735 for the US fluid ounce and 28.4131 for the imperial one, and knowing which the recipe means matters more than the precision of either. The two exist because they were defined as fractions of different gallons — a 128th of the US gallon and a 160th of the larger imperial gallon — with the counterintuitive result that the imperial fluid ounce is the smaller of the two. American recipes published after about 1900 mean US ounces. British recipes from before metrication mean imperial. Anything modern and British is far more likely to be in millilitres already. The bigger trap is not the four percent. It is that fluid ounces measure volume while the ounces used for flour, butter and sugar measure weight, and the same word is used for both. Eight fluid ounces of water weighs about eight and a third ounces; eight fluid ounces of flour weighs about four and a half. Any recipe mixing the two units without saying which is meant is ambiguous, and the reliable escape is to weigh dry ingredients in grams — which is why professional baking specifies volume for almost nothing.

Frequently asked questions