How to use the indentation hardness calculator
This page turns the force and the indentation size read off a hardness tester into a hardness number. For Brinell, enter the indenter ball diameter and the diameter of the impression; for Vickers, enter the mean diagonal. The result shows the hardness value, the area of the impression and the test force expressed in kilograms-force, which is useful for checking a tester reading or for seeing how much the hardness moves when the impression is measured again.
The equations are HBW = 0.102 x 2F / (piD(D - sqrt(D^2 - d^2))) for Brinell and HV = 0.102 x 1.8544F / d^2 for Vickers, with the force in newtons and the dimensions in millimeters. Both reduce to the force in kgf divided by the area of the impression, so the area is shown as its own line. These are the defining equations used in the test standards of the American Society for Testing and Materials family. The material consulted is secondary and current as of October 2026, so checking the standards themselves is recommended.
Conversion between Rockwell, Brinell and Vickers scales is not covered, because conversion tables depend on the material and heat treatment and are not confirmed in an authoritative source here. No reference hardness values per material are offered either. This is a reference aid and does not replace design work; review by a qualified engineer is required.
Frequently asked questions
No. Scale conversion tables depend on the material and are not confirmed in an authoritative source here, so no conversion is offered. The page computes only the defining equations of the indentation tests.
The defining equations treat the force in kilograms-force and the indentation area in square millimeters, and the resulting number is quoted without a unit by convention. The force in kgf is shown alongside for that reason.
The equation assumes the mean of both diagonals. When an indentation stretches to one side, a single diagonal moves the area and the hardness away from the defined value.