How this calculator works
Vickers testing uses a square-based diamond pyramid with a standard 136 degree angle between opposite faces. Average the two impression diagonals before squaring. The reported HV number uses the conventional kgf/mm2 basis, with exact standard gravity for force conversion. Changing the pyramid angle evaluates the geometric relation but no longer represents the standard Vickers indenter. Tensile strength cannot be reliably inferred without a material-specific empirical conversion, so this page reports hardness and contact pressure directly.
Formula
HV = 2 F sin(alpha/2)/(9.80665 d_mm^2); standard alpha = 136 degrees. Mean d = (d1+d2)/2.
Worked example
A 1 kgf load and 0.1 mm mean diagonal give HV = 185.43677 using the exact 136 degree geometry. At the same force, a 0.2 mm diagonal gives HV = 46.35919.
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Frequently asked questions
Should I average hardness from the two diagonals?
Average the diagonal lengths first, then calculate hardness from that mean.
Is HV a pressure?
Its numerical convention corresponds to kgf/mm2. The separate contact-pressure output is expressed in ordinary pressure units.
Does the force conversion depend on local gravity?
No. Standard kilogram-force uses the defined standard acceleration 9.80665 m/s2, regardless of the test location.