The bra size (also known as brassiere measurement or bust size) is the measure which indicates the size characteristics of a bra. Bra sizes are usually expressed as scales, with a number of systems being in use around the world. The scales take into account the band length and the cup size. From the wearer’s point of view, the main measures that are taken into account in determining the best bra fit for the wearer are the measures of the wearer around the torso below the breasts and over the breasts, which defines the band length. For convenience, because of the impracticality of measuring a woman’s breast size, the volume of the bra cup is based on the difference between these two measures.