Question 1

How do I convert HRC to HV, HB or HRB?

Accepted Answer

Select the scale you know (for example Rockwell C, HRC), type the value, and the calculator interpolates the equivalent Vickers (HV), Brinell (HB), Rockwell B (HRB), Rockwell A (HRA), Knoop (HK) and approximate tensile strength from the ASTM E140 / ISO 18265 conversion tables. The relationship is empirical, so results are approximate.

Question 2

Is hardness conversion accurate?

Accepted Answer

No conversion between hardness scales is exact. Each test uses a different indenter and load, so the correlations in ASTM E140 and ISO 18265 are empirical and were established mainly for carbon and low-alloy steels. For stainless, non-ferrous and specialty alloys use material-specific data, and for design decisions rely on a direct test of the actual material.

Question 3

How is hardness converted to tensile strength?

Accepted Answer

For steel, tensile strength Rm in MPa is roughly 3.3 to 3.4 times the Brinell number (HB), and ISO 18265 tabulates Rm against Vickers and Brinell hardness. The estimate is only meaningful up to about 600 HV; above that the correlation breaks down, so the tensile cells are left blank.

Question 4

When can I use HRB versus HRC?

Accepted Answer

Rockwell B (HRB, 1/16-inch ball, 100 kgf) is for softer metals up to about 240 HV / 100 HRB. Rockwell C (HRC, diamond cone, 150 kgf) is for hardened steel from about 20 HRC (240 HV) upward. The two scales barely overlap, which is why the calculator leaves HRB blank for hard steel and HRC blank for soft steel.

Question 5

What standards is this converter based on?

Accepted Answer

The conversion table follows ASTM E140 (Standard Hardness Conversion Tables for Metals) and ISO 18265 (Conversion of hardness values), with tensile-strength values consistent with ISO 18265 / DIN 50150. These cover unalloyed and low-alloy steels and cast steel.

HardnessConversion Calculator

Hardness
Conversion Calculator