Vickers Hardness Calculation, Hardness Test and Formula

Theory and interpretation

The Vickers test measures the residual impression left by a square-based diamond pyramid with a 136° angle between opposite faces. Measure both diagonals and enter their arithmetic mean d = (d1 + d2)/2. With force F in newtons and d in millimeters, this calculator uses HV = 0.1891F/d².

The coefficient combines the pyramid geometry and force-unit conversion. The displayed pressure equivalent is H = 9.8HV/1000 GPa, using the calculator’s rounded conversion. It is an indentation-hardness scale, not the yield stress.

The separate tensile-strength estimate uses σu = HV/0.3 MPa. This is a fixed empirical approximation, not a universal material law. No material, heat treatment or calibration data are supplied to this tool, so it cannot establish whether that estimate applies to your specimen. Use a validated material-specific correlation or tensile-test data for strength decisions.

Report the test force with hardness. Surface preparation, specimen thickness, dwell time, spacing and measurement quality affect the result; positive inputs alone do not establish compliance with a test standard. Do not assume that hardness scales or wear performance are interchangeable across materials.

References: Struers: Vickers hardness testing; SAE J417: approximate hardness conversions.

Worked example

Enter applied load 5 N and mean indentation diagonal 0.1 mm. The result is HV = 0.1891 × 5 / 0.1² = 94.55, corresponding to about 0.927 GPa with the calculator’s conversion. Average the two measured diagonals before entering the value. The separate tensile-strength estimate is an empirical approximation and must not replace a material-specific tensile test.