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Hardness Conversion Chart (HB, HRC, HV, HRB)

Equivalent hardness values across Brinell (HB), Vickers (HV) and Rockwell (HRC, HRA, HRB) scales, with approximate tensile strength, for carbon and low-alloy steels.

HVHBHRCHRAHRBTensile (MPa)
Conversions are approximate and this table applies to carbon and low-alloy steels only — austenitic stainless (304, 316) and tool steels have separate tables, and using the wrong one introduces 5–15% error. Rockwell C readings below about 20 HRC are unreliable; use HRB, HB or HV instead. Parenthesised HRC values fall outside the reliable range and are estimates only. Sources: ASTM E140 Table 1, ISO 18265 Annex A.

Standard: ASTM E140 / ISO 18265  ·  Data checked: 2026-10-14

Frequently asked questions

Why do I get a different answer from a different converter?

Because hardness conversion is not a physical law, it is a set of empirical tables that only hold for a stated material group. ASTM E140 and ISO 18265 both cover carbon and low-alloy steel, austenitic stainless, tool steel and non-ferrous alloys in separate sub-tables. Using the carbon steel table for 316 stainless introduces 5 to 15% error.

Why are some HRC values in brackets?

Because below about 20 HRC the diamond cone does not resolve soft materials well, so the conversion is unreliable. Those values are estimates and should not be quoted on a drawing — use HRB, HB or HV instead.

Which scale should I measure on?

The one that suits the hardness and the part. HV is the most linear and is what ISO 18265 recommends as the reference, but it needs a lab and a polished surface. HRC is convenient for hardened steel between 20 and 70. HRB or HB for soft material. HB is the usual choice for castings and large sections.

Is an online conversion the same as a calibrated test?

No. A conversion tells you the equivalent scale value, not the hardness of your part. Two parts that both read 30 HRC can have different microstructures and different wear behaviour, and a conversion cannot tell you that.

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