A **physical quantity** is a property of a material or system that can be quantified by measurement. A physical quantity can be expressed as a *value*, which is the algebraic multiplication of a *numerical value* and a *unit*. For example, the physical quantity mass can be quantified as *n* kg, where *n* is the numerical value and kg is the unit. A physical quantity possesses at least two characteristics in common. One is numerical magnitude and the other is the unit in which it is measured.

Measurable property of a material or system