Brinell Hardness Number Calculator
Calculate the Brinell Hardness Number (BHN) of a metal sample from the test load, indenter ball diameter, and resulting indentation diameter.
What the Brinell hardness test measures
The Brinell hardness test presses a hardened steel or carbide ball into a material’s surface under a known load, then measures the diameter of the resulting indentation. A smaller indentation for the same load means a harder material.
The formula
The Brinell Hardness Number is BHN = F / ((πD/2)(D – √(D² – d²))), where F is the applied load in kgf, D is the ball diameter, and d is the measured indentation diameter (both in mm). The result is expressed in HB (or kgf/mm²).
This calculator is for general materials science reference and education; official hardness testing should follow the applicable ASTM or ISO standard procedure.