Hardness conversion: HRC, HB, HV, HRB
The drawing says HRC 40–45, the bar certificate says HB 207, and the shop tester reads Vickers. Enter any value to see the other scales and the approximate tensile strength.
Quick answer
HRC 30 = HV 302 = HB 286, tensile strength about 950 MPa (138 ksi). HRC 40 = HV 392 = HB 371, HRC 60 = HV 697 = HB 654. Conversions are approximate and apply to steel, not austenitic stainless.
- Rockwell C
- —
- Vickers
- —
- Brinell
- —
- Rockwell A
- —
- Rockwell B
- —
- Tensile strength, approx.
- —
Steel hardness conversion chart
| HRC | HV | HB | HRA | HRB | Tensile, MPa | ksi |
|---|---|---|---|---|---|---|
| 68 | 940 | — | 85.6 | — | — | — |
| 67 | 900 | — | 85 | — | — | — |
| 66 | 865 | — | 84.5 | — | — | — |
| 65 | 832 | 739 | 83.9 | — | — | — |
| 64 | 800 | 722 | 83.4 | — | — | — |
| 63 | 772 | 705 | 82.8 | — | — | — |
| 62 | 746 | 688 | 82.3 | — | — | — |
| 61 | 720 | 670 | 81.8 | — | — | — |
| 60 | 697 | 654 | 81.2 | — | — | — |
| 59 | 674 | 634 | 80.7 | — | — | — |
| 58 | 653 | 615 | 80.1 | — | — | — |
| 57 | 633 | 595 | 79.6 | — | — | — |
| 56 | 613 | 577 | 79 | — | — | — |
| 55 | 595 | 560 | 78.5 | — | ≈ 2075 | ≈ 301 |
| 54 | 577 | 543 | 78 | — | ≈ 2015 | ≈ 292 |
| 53 | 560 | 525 | 77.4 | — | ≈ 1950 | ≈ 283 |
| 52 | 544 | 512 | 76.8 | — | ≈ 1880 | ≈ 273 |
| 51 | 528 | 496 | 76.3 | — | ≈ 1820 | ≈ 264 |
| 50 | 513 | 481 | 75.9 | — | ≈ 1760 | ≈ 255 |
| 49 | 498 | 469 | 75.2 | — | ≈ 1695 | ≈ 246 |
| 48 | 484 | 455 | 74.7 | — | ≈ 1635 | ≈ 237 |
| 47 | 471 | 443 | 74.1 | — | ≈ 1580 | ≈ 229 |
| 46 | 458 | 432 | 73.6 | — | ≈ 1530 | ≈ 222 |
| 45 | 446 | 421 | 73.1 | — | ≈ 1480 | ≈ 215 |
| 44 | 434 | 409 | 72.5 | — | ≈ 1435 | ≈ 208 |
| 43 | 423 | 400 | 72 | — | ≈ 1385 | ≈ 201 |
| 42 | 412 | 390 | 71.5 | — | ≈ 1340 | ≈ 194 |
| 41 | 402 | 381 | 70.9 | — | ≈ 1295 | ≈ 188 |
| 40 | 392 | 371 | 70.4 | — | ≈ 1250 | ≈ 181 |
| 39 | 382 | 362 | 69.9 | — | ≈ 1215 | ≈ 176 |
| 38 | 372 | 353 | 69.4 | — | ≈ 1180 | ≈ 171 |
| 37 | 363 | 344 | 68.9 | — | ≈ 1160 | ≈ 168 |
| 36 | 354 | 336 | 68.4 | — | ≈ 1115 | ≈ 162 |
| 35 | 345 | 327 | 67.9 | — | ≈ 1080 | ≈ 157 |
| 34 | 336 | 319 | 67.4 | — | ≈ 1055 | ≈ 153 |
| 33 | 327 | 311 | 66.8 | — | ≈ 1025 | ≈ 149 |
| 32 | 318 | 301 | 66.3 | — | ≈ 1000 | ≈ 145 |
| 31 | 310 | 294 | 65.8 | — | ≈ 980 | ≈ 142 |
| 30 | 302 | 286 | 65.3 | — | ≈ 950 | ≈ 138 |
| 29 | 294 | 279 | 64.7 | — | ≈ 930 | ≈ 135 |
| 28 | 286 | 271 | 64.3 | — | ≈ 910 | ≈ 132 |
| 27 | 279 | 264 | 63.8 | — | ≈ 880 | ≈ 128 |
| 26 | 272 | 258 | 63.3 | — | ≈ 860 | ≈ 125 |
| 25 | 266 | 253 | 62.8 | — | ≈ 840 | ≈ 122 |
| 24 | 260 | 247 | 62.4 | 101 | ≈ 825 | ≈ 120 |
| 23 | 254 | 243 | 62 | 100 | ≈ 805 | ≈ 117 |
| 22 | 248 | 237 | 61.5 | 99 | ≈ 785 | ≈ 114 |
| 21 | 243 | 231 | 61 | 98.5 | ≈ 770 | ≈ 112 |
| 20 | 238 | 226 | 60.5 | 97.8 | ≈ 760 | ≈ 110 |
| — | 230 | 219 | — | 96.7 | ≈ 730 | ≈ 106 |
| — | 222 | 212 | — | 95.5 | ≈ 705 | ≈ 102 |
| — | 213 | 203 | — | 93.9 | ≈ 675 | ≈ 98 |
| — | 204 | 194 | — | 92.3 | ≈ 650 | ≈ 94 |
| — | 196 | 187 | — | 90.7 | ≈ 620 | ≈ 90 |
| — | 188 | 179 | — | 89.5 | ≈ 600 | ≈ 87 |
| — | 180 | 171 | — | 87.1 | ≈ 580 | ≈ 84 |
| — | 173 | 165 | — | 85.5 | ≈ 550 | ≈ 80 |
| — | 166 | 158 | — | 83.5 | ≈ 530 | ≈ 77 |
| — | 160 | 152 | — | 81.7 | ≈ 515 | ≈ 75 |
What it means at the lathe
Raw and normalized bar is usually specified in HB — ISO P (steel) inserts. The harder the quenched-and-tempered steel, the lower the cutting speed with the same inserts. Hardened steel, from about HRC 45, is ISO group H: inserts for hard materials (often CBN), small depth of cut and a rigid setup. ISO groups P, M, K, N, S, H.
HRC below 20 is not used — soft steel is measured in Brinell (HB) or Rockwell B (HRB). HRB above 100 is not used either — that's HRC territory. That's why some cells are empty.
Conversion between scales is empirical: there's no exact formula, and different steels and heat treatments give slightly different ratios. If the drawing specifies HRC, accept the part by an HRC measurement, not by converting from HB.
Values per SAE J417 and ASTM E140 (Table 1: non-austenitic steels), cross-checked against several published charts. HB is a 10 mm ball at 3000 kgf; from about HRC 54 a tungsten carbide ball (HBW). Tensile strength is approximate. Not valid for non-ferrous metals or austenitic stainless steel.
Steel grades and their equivalents — see the steel grade equivalents chart.