The Brinell hardness typical test uses a 10 millimetres (0.39 in) diameter steel ball and the lod force is 3,000 kgf force.
BHN = (2*P) / [ (pi*D)(D - sqrt(D2-d2)) ]
For example, when Loda force is 3000 kilogram force, steel ball diameter is 10 millimeter, depression diameter is 9 millimeter, the Brinell Hardness Number (BHN) will be 33.87331668681452.