Fluid ounce

A fluid ounce (abbreviated fl oz, fl. oz. or oz. fl., old forms ℥, fl ℥, f℥, ƒ ℥) is a unit of volume (also called capacity) typically used for measuring liquids. It is equivalent to approximately 30 millilitres. Whilst various definitions have been used throughout history, two remain in common use: the imperial and the United States customary fluid ounce. An imperial fluid ounce is ⁄₂₀ of an imperial pint, ⁄₁₆₀ of an imperial gallon or approximately 28.4 ml. A US fluid ounce is ⁄₁₆ of a US fluid pint, ⁄₁₂₈ of a US liquid gallon or approximately 29.6 ml. The fluid ounce is distinct from the ounce, a unit of weight or mass, although they do have a historical relationship, and it is sometimes referred to simply as an "ounce" where context makes the meaning clear.