Direct answer
How Many mL in a Fluid Ounce? 1 US fl oz ≈ 29.5735 mL
1 US fluid ounce equals about 29.5735 milliliters. Drink-label answer with UK fl oz caveat and converter links.
Question
How many milliliters are in a fluid ounce?
1 US fluid ounce (fl oz) equals approximately 29.5735 milliliters (mL).
1 US fl oz
≈ 29.5735 mL
12 US fl oz
≈ 354.882 mL
1 UK fl oz
≈ 28.4131 mL
Explanation
US drink labels and recipes usually mean the US customary fluid ounce.
Multiply US fl oz by 29.5735 to get milliliters. Example: 12 fl oz ≈ 355 mL.
The UK (imperial) fluid ounce is slightly smaller: about 28.4131 mL. Confirm which standard a recipe uses.
Important caveat
Fluid ounces are volume, not weight ounces. This page uses the US fluid ounce unless otherwise noted.