What is the difference between troy ounce and imperial ounce?
units of mass International avoirdupois ounce 28.349523 g International troy ounce 31.1034768 g Apothecaries’ ounce 31.1034768 g units of volume 1 imperial fluid ounce 28.4130625 millilitres 1 U.S. fluid ounce 29.5735295625 millilitres not sure which ones you want, but it’s one of these. Watch our for the two totally different ounces, one of mass, one of volume.