Engineering · Reference
Hardness conversion chart.
Rockwell C, Rockwell B, Vickers, Brinell, and approximate tensile strength — converted from Mitutoyo's approximate reference for steel. Use this when a drawing calls out hardness in one scale and your inspection equipment reads another, or when you need to estimate ultimate tensile from a hardness reading.
Interactive Dashboard
Hardness Scale Comparator
Approximate steel-reference comparisons, not inspection acceptance or alloy identification. Rows are transcribed from Mitutoyo Bulletin 2059(2). HRB-region Vickers values are withheld: the source has a separate Knoop column and a combined HB/HV heading, not a separately identified Vickers test column. A dash means unavailable here, not zero.
Type a value or tap a preset.
Snaps to the nearest available source row, not an interpolated result.
Physical Test Geometry
Rockwell Brale Indenter: Ground diamond cone with a 120° tip angle and a 0.2 mm spherical radius. The minor load establishes reference depth, and the major load measures the delta indentation depth.
Approximate UTS & Alloy Compatibility
Pre-hardened State (32 HRC): Readily machinable with standard carbide tooling. Chips break cleanly. Suitable for highly complex custom shafts and tooling fixtures where post-machining heat treatment distortion must be fully avoided.
Master Conversion Table
| Index | Rockwell C (HRC) | Rockwell B (HRB) | Vickers (HV) | Brinell (HB) | UTS (ksi) | UTS (MPa) |
|---|---|---|---|---|---|---|
| #1 | 68 | — | 940 | — | — | — |
| #2 | 65 | — | 832 | 739 | — | — |
| #3 | 62 | — | 746 | 688 | — | — |
| #4 | 60 | — | 697 | 654 | — | — |
| #5 | 58 | — | 653 | 615 | 338 | 2330 |
| #6 | 56 | — | 613 | 577 | 313 | 2158 |
| #7 | 54 | — | 577 | 543 | 292 | 2013 |
| #8 | 52 | — | 544 | 512 | 273 | 1882 |
| #9 | 50 | — | 513 | 481 | 255 | 1758 |
| #10 | 48 | — | 484 | 455 | 238 | 1641 |
| #11 | 46 | — | 458 | 432 | 221 | 1524 |
| #12 | 44 | — | 434 | 409 | 208 | 1434 |
| #13 | 42 | — | 412 | 390 | 194 | 1338 |
| #14 | 40 | — | 392 | 371 | 182 | 1255 |
| #15 | 38 | — | 372 | 353 | 171 | 1179 |
| #16 | 36 | — | 354 | 336 | 161 | 1110 |
| #17 | 34 | — | 336 | 319 | 152 | 1048 |
| #18 | 32 | — | 318 | 301 | 146 | 1007 |
| #19 | 30 | — | 302 | 286 | 138 | 951 |
| #20 | 28 | — | 286 | 271 | 131 | 903 |
| #21 | 26 | — | 272 | 258 | 125 | 862 |
| #22 | 24 | — | 260 | 247 | 119 | 820 |
| #23 | 22 | — | 248 | 237 | 115 | 793 |
| #24 | 20 | — | 238 | 226 | 110 | 758 |
| #25 | — | 98 | 0 | 228 | 109 | 752 |
| #26 | — | 95 | 0 | 210 | 100 | 689 |
| #27 | — | 92 | 0 | 195 | 92 | 634 |
| #28 | — | 90 | 0 | 185 | 89 | 614 |
| #29 | — | 86 | 0 | 169 | 83 | 572 |
| #30 | — | 80 | 0 | 150 | 72 | 496 |
| #31 | — | 75 | 0 | 137 | 66 | 455 |
| #32 | — | 70 | 0 | 125 | 61 | 421 |
| #33 | — | 60 | 0 | 107 | — | — |
| #34 | — | 50 | 0 | — | — | — |
How to use this
Scale selection & caveats.
- HRC for hardened steel ≥ 20 HRC.
Diamond cone, 150 kgf load. Standard for tool steel, hardened 4140/4340, hardened 17-4PH (H900–H1075). Below 20 HRC the readings get unreliable.
- HRB for soft-to-medium steel and some non-ferrous.
1/16″ ball, 100 kgf load. Use for annealed steel, brass, aluminum bronze, hard plastics. Above ~100 HRB switch to HRC.
- HV (Vickers) for everything.
Diamond pyramid, variable load. Single scale that covers soft aluminum to carbide. Common for thin coatings, hardened-case-depth measurement, and material-research work.
- HB (Brinell) for thicker work and castings.
10 mm ball, 3000 kgf for steel. Large indent gives good average for non-uniform material. Common on cast-iron specs, large forgings. The HB column here is the source’s 3000 kgf / 10 mm ball column; no carbide-ball test equivalence is implied.
- Tensile strength is approximate.
The UTS values are the approximate steel correlations published in Mitutoyo Bulletin 2059(2), not independently measured strengths or design allowables. A dash means that this source does not supply a value. Do not infer alloy identity or acceptance from a converted reading.
- Non-steel conversions are not transferable.
The values above are for steel. For aluminum, copper, titanium, and other non-ferrous, use material-specific conversion tables (often in the alloy datasheet) or measure on multiple scales directly.
Keep exploring
Related tools & references
How H900 through H1150 map to the HRC values in this table.
How hardening, tempering, and aging set the hardness you're converting.
Estimate effective case depth from a surface-hardness target.
Companion property reference for the same alloy families.
Stiffness values to pair with strength estimated from hardness.
Have a part that needs to be made right?
Tell us about your part and we'll get back to you promptly. Aerospace, medical, defense, and semiconductor production work welcome.Email CAD models and drawings to sales@digitalmachine.com, including ITAR, EAR, CUI and AS9100 work. Keep controlled technical data out of web forms.
First articles through full production runs