Question: are ounces mass or volume?
Answer: The ounce (abbreviated oz; apothecary symbol: ℥) is a unit of mass, weight, or volume used in most British derived customary systems of measurement. The common avoirdupois ounce (approximately 28.3 g) is ​1⁄16 of a common avoirdupois pound; this is the United States customary and British imperial ounce.