A measure of the hardness of metals and alloys. It involves pressing a small, hardened steel ball into the surface of the metal being tested by a known loading force. The number is the ratio of the mass of the load in kilograms to the area of the depression created by the ball in square millimetres. Typical numbers range from 60 (soft) to 800 (hard). It is named after Swedish metallurgist J. A. Brinell (1849–1925).