Hardness Conversion Chart
Approximate equivalents between Rockwell C, Vickers, Brinell, Rockwell A and the superficial 15N and 30N scales for carbon, alloy and tool steel from HRC 20 to 68, with an estimated tensile strength. Use the converter for readings between rows.
Hardness converter
Enter a reading on any scale. Values between table rows are interpolated.
Pick a scale and enter a reading to see the equivalents for carbon and alloy steel.
Steel hardness conversion table
| HRC | HV | HB | HRA | HR15N | HR30N | Tensile (ksi) | Tensile (MPa) |
|---|---|---|---|---|---|---|---|
| 68 | 940 | Beyond the Brinell range | 85.6 | 93.2 | 84.4 | Not estimated | Not estimated |
| 67 | 900 | Beyond the Brinell range | 85.0 | 92.9 | 83.6 | Not estimated | Not estimated |
| 66 | 865 | Beyond the Brinell range | 84.5 | 92.5 | 82.8 | Not estimated | Not estimated |
| 65 | 832 | Beyond the Brinell range | 83.9 | 92.2 | 81.9 | Not estimated | Not estimated |
| 64 | 800 | Beyond the Brinell range | 83.4 | 91.8 | 81.1 | Not estimated | Not estimated |
| 63 | 772 | Beyond the Brinell range | 82.8 | 91.4 | 80.1 | Not estimated | Not estimated |
| 62 | 746 | Beyond the Brinell range | 82.3 | 91.1 | 79.3 | Not estimated | Not estimated |
| 61 | 720 | Beyond the Brinell range | 81.8 | 90.7 | 78.4 | Not estimated | Not estimated |
| 60 | 697 | Beyond the Brinell range | 81.2 | 90.2 | 77.5 | Not estimated | Not estimated |
| 59 | 674 | 634 (carbide ball required) | 80.7 | 89.8 | 76.6 | Not estimated | Not estimated |
| 58 | 653 | 615 (carbide ball required) | 80.1 | 89.3 | 75.7 | Not estimated | Not estimated |
| 57 | 633 | 595 (carbide ball required) | 79.6 | 88.9 | 74.8 | Not estimated | Not estimated |
| 56 | 613 | 577 (carbide ball required) | 79.0 | 88.3 | 73.9 | Not estimated | Not estimated |
| 55 | 595 | 560 (carbide ball required) | 78.5 | 87.9 | 73.0 | 301 | 2075 |
| 54 | 577 | 543 (carbide ball required) | 78.0 | 87.4 | 72.0 | 292 | 2015 |
| 53 | 560 | 525 (carbide ball required) | 77.4 | 86.9 | 71.2 | 283 | 1950 |
| 52 | 544 | 512 (carbide ball required) | 76.8 | 86.4 | 70.2 | 273 | 1880 |
| 51 | 528 | 496 (carbide ball required) | 76.3 | 85.9 | 69.4 | 264 | 1820 |
| 50 | 513 | 481 (carbide ball required) | 75.9 | 85.5 | 68.5 | 255 | 1760 |
| 49 | 498 | 469 (carbide ball required) | 75.2 | 85.0 | 67.6 | 246 | 1695 |
| 48 | 484 | 455 (carbide ball required) | 74.7 | 84.5 | 66.7 | 238 | 1640 |
| 47 | 471 | 443 | 74.1 | 83.9 | 65.8 | 229 | 1580 |
| 46 | 458 | 432 | 73.6 | 83.5 | 64.8 | 221 | 1525 |
| 45 | 446 | 421 | 73.1 | 83.0 | 64.0 | 215 | 1480 |
| 44 | 434 | 409 | 72.5 | 82.5 | 63.1 | 208 | 1435 |
| 43 | 423 | 400 | 72.0 | 82.0 | 62.2 | 201 | 1385 |
| 42 | 412 | 390 | 71.5 | 81.5 | 61.3 | 194 | 1340 |
| 41 | 402 | 381 | 70.9 | 80.9 | 60.4 | 188 | 1295 |
| 40 | 392 | 371 | 70.4 | 80.4 | 59.5 | 182 | 1255 |
| 39 | 382 | 362 | 69.9 | 79.9 | 58.6 | 177 | 1220 |
| 38 | 372 | 353 | 69.4 | 79.4 | 57.7 | 171 | 1180 |
| 37 | 363 | 344 | 68.9 | 78.8 | 56.8 | 166 | 1145 |
| 36 | 354 | 336 | 68.4 | 78.3 | 55.9 | 161 | 1110 |
| 35 | 345 | 327 | 67.9 | 77.7 | 55.0 | 157 | 1080 |
| 34 | 336 | 319 | 67.4 | 77.2 | 54.2 | 153 | 1055 |
| 33 | 327 | 311 | 66.8 | 76.6 | 53.3 | 149 | 1025 |
| 32 | 318 | 301 | 66.3 | 76.1 | 52.1 | 145 | 1000 |
| 31 | 310 | 294 | 65.8 | 75.6 | 51.3 | 141 | 970 |
| 30 | 302 | 286 | 65.3 | 75.0 | 50.4 | 138 | 950 |
| 29 | 294 | 279 | 64.7 | 74.5 | 49.5 | 135 | 930 |
| 28 | 286 | 271 | 64.3 | 73.9 | 48.6 | 131 | 905 |
| 27 | 279 | 264 | 63.8 | 73.3 | 47.7 | 128 | 885 |
| 26 | 272 | 258 | 63.3 | 72.8 | 46.8 | 125 | 860 |
| 25 | 266 | 253 | 62.8 | 72.2 | 45.9 | 122 | 840 |
| 24 | 260 | 247 | 62.4 | 71.6 | 45.0 | 119 | 820 |
| 23 | 254 | 243 | 62.0 | 71.0 | 44.0 | 117 | 805 |
| 22 | 248 | 237 | 61.5 | 70.5 | 43.2 | 115 | 795 |
| 21 | 243 | 231 | 61.0 | 69.9 | 42.3 | 112 | 770 |
| 20 | 238 | 226 | 60.5 | 69.4 | 41.5 | 110 | 760 |
HB is Brinell with a 10 mm tungsten carbide ball at 3000 kgf (HBW 10/3000). * Above about 450 HB a hardened steel ball flattens and reads low, so a carbide ball is required; current ASTM E10 uses carbide balls throughout and stops at 650 HBW, so HB is blank above HRC 59.
Tensile strength is an approximation for through-hardened steel, rounded (MPa to the nearest 5), and is not given above HRC 55. Values follow the empirical ASTM E140 lineage for non-austenitic steel; they are not valid for austenitic stainless, nonferrous metals, cold-worked material or case-hardened surfaces.
Need parts machined and hardened to a spec? , or read about heat treating.
Which scale to call out
- Rockwell C for through-hardened steel from about 20 to 68 HRC: shafts, pins, dies, tooling. It is fast and needs little surface prep.
- Rockwell B or Brinell for annealed and normalized steel, castings and forgings. Brinell's large ball averages over coarse grain and is the usual scale for plate and forging specs.
- Superficial (15N, 30N) or Rockwell A for thin material and hard, shallow cases, where a full Rockwell C test would punch through. As a rule, the part must be at least ten times as thick as the indentation is deep.
- Vickers or Knoop microhardness for case depth traverses on carburized and nitrided parts and for small features.
- Give a range and a location. "58-62 HRC on the bearing journal" is testable; "hardened" is not.
Related processes, materials and charts
Frequently asked questions
- How accurate is a hardness conversion?
- It is an estimate. Each scale presses a different indenter into the metal with a different load, and the tables were built by testing the same steels on each scale. Alloy, heat treatment, cold work and surface condition all shift the relationship. If a spec calls for a scale, test on that scale; do not accept a converted number in its place.
- What is 4140 pre-hard in Brinell?
- Pre-hardened 4140 bar is usually about 28 to 32 HRC, which this table puts at roughly 271 to 301 HB.
- Why does the chart start at HRC 20?
- The Rockwell C scale loses accuracy below about 20. Softer steel is tested on Rockwell B (a 1/16 in ball at 100 kgf) or with Brinell.
- How do I estimate tensile strength from hardness?
- For through-hardened carbon and alloy steel, tensile strength in ksi is roughly half the Brinell number, or in MPa roughly 3.4 times it. The chart column follows that relationship up to HRC 55. It does not apply to case-hardened parts, cast iron or nonferrous metals.
- Can I use this for stainless steel or aluminum?
- Not reliably. The table is for non-austenitic (carbon, alloy and tool) steels. Austenitic stainless, aluminum, copper alloys and nickel alloys each have their own conversion relationships.
