Hardness Conversion Chart

24 April 2026

Verified by Rachel Mayfield, Supply Chain Analyst - April 2026

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Hardness conversion table cross-referencing Rockwell C (HRC), Brinell (HB 10/3000), Vickers (HV), and approximate tensile strength in MPa for carbon and alloy steels. Hardness Conversion Chart Values are per ASTM E140 and ISO 18265. Brinell values above HRC 40 are generally not reliable because the test ball deforms, so those cells are left blank. Tensile strength conversions above HRC 52 are outside the validated range and are omitted.

HRC HB (Brinell) HV (Vickers) Approx. Tensile Strength (MPa)
68 - 940 -
67 - 900 -
66 - 865 -
65 - 832 -
64 - 800 -
63 - 772 -
62 - 746 -
61 - 720 -
60 - 697 -
59 - 674 -
58 - 653 -
57 - 633 -
56 - 613 -
55 - 595 -
54 - 577 -
53 - 560 -
52 - 544 2180
51 - 528 2110
50 - 513 2050
49 - 498 1990
48 - 484 1930
47 - 471 1870
46 - 458 1820
45 - 446 1760
44 - 434 1710
43 - 423 1660
42 - 412 1610
41 - 402 1560
40 371 392 1510
39 362 382 1460
38 353 372 1420
37 344 363 1370
36 336 354 1330
35 327 345 1290
34 319 336 1250
33 311 327 1210
32 301 318 1170
31 294 310 1140
30 286 302 1110
29 279 294 1080
28 271 286 1050
27 264 279 1020
26 258 272 990
25 253 266 970
24 247 260 950
23 243 254 930
22 237 248 910
21 231 243 880
20 226 238 860

How to use the hardness conversion chart

Find your known hardness value in the appropriate column and read across for the equivalent in other scales. These conversions are approximate - they're based on statistical correlations for carbon and alloy steels, not exact mathematical relationships. For austenitic stainless steels, non-ferrous metals, or case-hardened surfaces, use dedicated conversion tables for those materials.

Rockwell C (HRC) is the standard scale for hardened steels (typically 20-68 HRC). Brinell (HB) is common for softer steels and castings (typically 100-450 HB). Vickers (HV) covers the full range and is useful for thin sections and surface hardness testing because it uses a smaller indentation.

Tensile strength conversion is the least accurate column. It's useful for rough estimates but shouldn't replace actual tensile testing when strength values are needed for design calculations.

Related standards

References

  1. ASTM E140-12b(2019)e1 - Standard hardness conversion tables for metals
  2. ISO 18265:2013 - Metallic materials - hardness conversion tables

Where this data comes from: Supplier listings are verified against Companies House public records. Product specifications reference published ISO, BS, and DIN standards. Trade body data is sourced from official member directories.

Frequently Asked Questions

What HRC is equivalent to 300 HB Brinell?

300 HB Brinell is approximately equivalent to 32 HRC Rockwell C (with an HV Vickers value of around 318). The approximate tensile strength at this hardness is 1170 MPa. These conversions are per ASTM E140 for carbon and alloy steels.

Can I convert hardness to tensile strength?

Yes, but only approximately. Hardness-to-tensile-strength conversion is an empirical correlation, not an exact relationship. It works reasonably well for plain carbon and low-alloy steels in the range of about 20-52 HRC. For other materials or heat treatment conditions, the correlation may not hold. Always test tensile strength directly for critical applications.

Why are some Brinell values blank in the conversion chart?

Above about 40 HRC (371 HB), the Brinell test ball starts to deform, making the results unreliable. The standard Brinell test uses a 10mm tungsten carbide ball with 3000 kgf load, and at high hardness the ball flattens. For hardened steels above 40 HRC, use Rockwell C or Vickers instead.

What is the Hardness Conversion Chart primarily used for?

The Hardness Conversion Chart is a reference tool that cross-references Rockwell C (HRC), Brinell (HB 10/3000), and Vickers (HV) hardness scales, providing approximate tensile strength in MPa for carbon and alloy steels. It adheres to standards ASTM E140 and ISO 18265.

Why are Brinell values above HRC 40 unreliable according to the Hardness Conversion Chart?

Brinell hardness values above HRC 40 are generally not reliable because the test ball deforms under higher pressures, leading to inaccurate readings. As a result, these cells are left blank in the chart.

How does one select an appropriate scale for measuring hardness using the Hardness Conversion Chart?

The selection of a hardness measurement scale depends on the material's properties and the required precision. For instance, Vickers is suitable for thin or small parts due to its wide range of applicability from soft metals to extremely hard materials.

Which standards does the Hardness Conversion Chart follow?

The chart adheres to ASTM E140 and ISO 18265 standards, providing a scientifically validated method for hardness conversion among Rockwell C (HRC), Brinell (HB 10/3000), Vickers (HV), and approximate tensile strength in MPa.

Can you recommend any UK suppliers for obtaining Hardness Conversion Chart materials?

British companies like Bowers硬度转换图表供应商信息似乎没有直接提供在给定的页面内容中。不过，英国的一些知名金属处理和测试设备公司通常会提供此类图表或相关服务。

What is the cost and availability of the Hardness Conversion Chart for UK engineers?

The Hardness Conversion Chart itself, as a reference tool on websites like mlc.org.uk, is typically free to access online. Physical copies or specialized software might have costs associated with them from suppliers.

How does the Hardness Conversion Chart handle tensile strength conversions above HRC 52?

Tensile strength conversions for hardness values above HRC 52 are outside the validated range according to ASTM E140 and ISO 18265 standards, so these values are omitted from the chart.

References