Engineering · Reference
Hardness conversion chart.
Rockwell C, Rockwell B, Vickers, Brinell, and approximate tensile strength — converted per ASTM E140 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.
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Hardness Scale Comparator
Type a hardness value in any scale (or click a preset) to convert between Rockwell, Vickers, and Brinell, and estimate tensile strength.
Type a value or tap a preset.
Snaps to the nearest row in the ASTM E140 table.
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 (HBW) | UTS (ksi) | UTS (MPa) |
|---|---|---|---|---|---|---|
| #1 | 68 | — | 940 | — | — | — |
| #2 | 65 | — | 832 | 739 | — | — |
| #3 | 62 | — | 746 | 688 | — | — |
| #4 | 60 | — | 697 | 654 | — | — |
| #5 | 58 | — | 653 | 615 | — | — |
| #6 | 56 | — | 613 | 577 | — | — |
| #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 | — | 411 | 388 | 193 | 1331 |
| #14 | 40 | — | 392 | 371 | 182 | 1255 |
| #15 | 38 | — | 372 | 353 | 171 | 1179 |
| #16 | 36 | — | 354 | 336 | 161 | 1110 |
| #17 | 34 | — | 336 | 319 | 151 | 1041 |
| #18 | 32 | — | 318 | 301 | 143 | 986 |
| #19 | 30 | — | 302 | 286 | 136 | 938 |
| #20 | 28 | — | 286 | 271 | 129 | 889 |
| #21 | 26 | — | 273 | 258 | 123 | 848 |
| #22 | 24 | — | 261 | 247 | 117 | 807 |
| #23 | 22 | — | 250 | 237 | 112 | 772 |
| #24 | 20 | 100 | 240 | 226 | 107 | 738 |
| #25 | — | 98 | 228 | 228 | 102 | 703 |
| #26 | — | 95 | 210 | 210 | 98 | 676 |
| #27 | — | 92 | 195 | 195 | 93 | 641 |
| #28 | — | 90 | 185 | 185 | 90 | 621 |
| #29 | — | 86 | 169 | 169 | 86 | 593 |
| #30 | — | 80 | 150 | 150 | 81 | 558 |
| #31 | — | 75 | 137 | 137 | — | — |
| #32 | — | 70 | 125 | 125 | — | — |
| #33 | — | 60 | 107 | 107 | — | — |
| #34 | — | 50 | 93 | 93 | — | — |
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.
- HBW (Brinell) for thicker work and castings.
10 mm tungsten-carbide ball, 3000 kgf for steel. Large indent gives good average for non-uniform material. Common on cast-iron specs, large forgings.
- Tensile strength is approximate.
The UTS columns follow ASTM A370 Table 3 / SAE J417 for non-austenitic steel (E140 itself converts hardness to hardness only — it publishes no tensile column). The quick rule of thumb tensile ≈ 500 × HBW (psi) tracks the table loosely — a few percent high below ~40 HRC, several percent low above ~45 HRC — and above ~55 HRC no correlation is published at all (the table shows “—”). Steel only, estimates only — never a substitute for an actual tensile test.
- 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.
Technically reviewed by the True Precision Machining engineering team · Last reviewed June 2026
Standards referenced: ASTM E140, ASTM E18, ASTM E10, ASTM E384
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