Reference & Charts
Hardness Conversion Chart
Approximate conversions between Rockwell C (HRC), Vickers (HV), and Brinell (HB) hardness for steels, with the rough tensile strength each implies. A quick shop reference for reading across hardness scales — approximate and material-dependent, per ASTM E140.
10 entries · Last verified: 2026-07-10
Hardness is measured on several scales — Rockwell C (HRC) for hardened steels, Vickers (HV) across the full range, and Brinell (HB) for softer and larger parts. There is no exact universal conversion between them: ASTM E140 provides tables that are approximate and depend on the material. The values below are the typical published conversions for steels, useful for reading a spec across scales — but for anything critical, measure on the actual part with the specified method.
| Hardness | Vickers(HV) | Brinell(HB) | Tensile(MPa) | Tensile(ksi) |
|---|---|---|---|---|
| 65 HRC | 832 HV | — | — | — |
| 60 HRC | 697 HV | 654 HB | — | — |
| 55 HRC | 595 HV | 560 HB | 2075 MPa | 301 ksi |
| 50 HRC | 513 HV | 481 HB | 1740 MPa | 252 ksi |
| 45 HRC | 446 HV | 421 HB | 1480 MPa | 215 ksi |
| 40 HRC | 392 HV | 371 HB | 1289 MPa | 187 ksi |
| 35 HRC | 345 HV | 327 HB | 1120 MPa | 162 ksi |
| 30 HRC | 302 HV | 286 HB | 979 MPa | 142 ksi |
| 25 HRC | 266 HV | 253 HB | 862 MPa | 125 ksi |
| 20 HRC | 238 HV | 226 HB | 774 MPa | 112 ksi |
Frequently asked
- Why isn't hardness conversion exact?
- Each test measures resistance to indentation differently (cone vs. pyramid vs. ball, different loads). The relationship between them varies with the material's composition and structure, so a converted value is an estimate. ASTM E140 tables — the basis for charts like this — are explicitly approximate and steel-specific.
- How do I estimate tensile strength from hardness?
- For steels, ultimate tensile strength in ksi is very roughly 0.5 × HB, or read it from the chart. It's an approximation for carbon and low-alloy steels only — it doesn't hold for many stainless, non-ferrous, or heavily worked materials.
- Why are some Brinell and tensile cells blank?
- Above about 60 HRC the standard Brinell test (10 mm ball) is out of its valid range, and the hardness-to-tensile approximation breaks down for very hard, low-ductility steel — so those cells are left blank rather than showing a misleading number.
Sources
- ASTM E140 — Standard Hardness Conversion Tables for Metals (approximate, material-dependent)
- SAE J417 — hardness/tensile relationships for steels