Vickers Hardness Number Calculator

Estimate the material hardness for your test specimen using the Vickers hardness number calculator.

Vickers hardness454.1 HV1.8544 × 30 kgf ÷ (0.35 mm)²

Estimated tensile strength1,567 MParoughly 3.45 × HB for steels — an empirical correlation, not a physical law, and it does not hold for non-ferrous alloys

In ksi227.1 ksiabout HB ÷ 2, the imperial rule of thumb

Approximate Rockwell C47.4 HRCinterpolated from published reference points, not a formula — there is no algebraic relation between the scales

Approximate Rockwell Btoo hard for the B scale — use HRC above about 241 HBthe B and C scales overlap only narrowly, around 229–241 HB

Hardness scales are not interchangeableconversions are empiricaleach test loads the material differently, so published conversion tables are correlations fitted to particular alloy families and can be several points out on others

Against annealed aluminium18.166×about 25 HB

Against mild steel3.784×about 120 HB

Against hardened tool steel0.699×about 650 HB

The formula

HB = 2P ÷ (πD(D − √(D²−d²))); HV = 1.8544F ÷ d²

Hardness is a test result, not a material property

Unlike Young's modulus or yield strength, hardness is defined by the procedure used to measure it. Brinell presses a ball, Vickers a diamond pyramid, Rockwell measures depth rather than width. Each loads the material differently, so the numbers are not the same quantity and conversions between them are empirical correlations rather than exact relations.

Brinell has a further catch: the result depends on the load and ball size, so the ratio of load to diameter squared must match the material class — 30 for steel, 10 for copper alloys, 5 for aluminium — or two readings on the same metal will disagree. The indentation should also fall between 24% and 60% of the ball diameter; outside that the geometry stops being valid.

The correlation with tensile strength, about 3.45 MPa per Brinell point for steels, is genuinely useful for a quick estimate and genuinely approximate. It reflects that both properties depend on resistance to plastic flow, but it is a fitted relationship for ferrous alloys and does not carry over to aluminium or copper.