Hardness Conversion Chart —
HRC, HRB, Brinell, Vickers, and Tensile

Hardness Conversion Table

One table, hardest to softest. The upper rows are the Rockwell C range for hardened and tempered steels (roughly 20 to 68 HRC); the lower rows are the Rockwell B range for soft and annealed stock. Dashes mark where a scale is outside its useful range: Brinell readings above about 615 HB exceed the ball indenter's limit, HRB loses resolution above 100 where drawings switch to HRC (the scales meet around 100 HRB ≈ 22 to 24 HRC), and the tensile estimate is not reliable above roughly 45 HRC. In the soft range Vickers and Brinell values are essentially equal.[1]

How to Use This Chart

Conversions are approximations. Each scale measures resistance to a different indenter at a different load, so there is no exact mathematical conversion. ASTM E140 publishes the accepted correlation tables for non-austenitic steels, and this chart follows them. Treat any converted value as ±2 points or so, and never convert when the drawing specifies the test method: a callout of "28-32 HRC" must be verified on the C scale, not converted from a Brinell reading.[1]

The tensile estimate. The tensile column uses the classic steel approximation of 500 × HB in psi. It holds within roughly ±10% for carbon and low-alloy steels up to about 400 HB; above roughly 45 HRC the correlation weakens, so no estimate is shown there. It does not apply to aluminum, copper alloys, or austenitic stainless.[2]

Which scale will you see? Hardened alloy steel parts (4140, 4340) and tool steels call out HRC. Bar stock certs for mild steel usually report Brinell. Vickers appears on lab reports and thin case-hardened layers because its microindenter reads shallow cases that a Brinell ball would punch through. See our heat treatment glossary for what the conditions behind these numbers mean.