Question: what is the difference between us fluid ounce and imperial fluid ounce?
Answer: An imperial fluid ounce is ​1⁄20 of an imperial pint, ​1⁄160 of an imperial gallon or approximately 28.41 ml. A US fluid ounce is ​1⁄16 of a US fluid pint and ​1⁄128 of a US liquid gallon or approximately 29.57 ml, making it about 4.08% larger than the imperial fluid ounce.