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Hardness Conversion Chart

Rockwell C & B, Vickers, Brinell, and approximate tensile strength — converted from Mitutoyo Bulletin 2059(2).

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Dual-scale hardness bar, drawn to scale and linear in Rockwell C: a sectioned steel bar with HRC graduations 20, 30, 40, 50, 60, and 65 on top and the equivalent Vickers values 238, 302, 392, 513, 697, and 832 HV under each graduation. Red markers above the bar locate mild steel below 20 HRC, prehard 4140 at 28 to 32, 17-4PH H900 at 40 to 44, hardened tool steel at 60 to 62, and a file near 65. Equal 10-point HRC steps stretch from 64 HV at the soft end to 184 HV at the hard end.MILD STEEL<20 HRC17-4PH H90040–44 HRCFILE~65 HRC4140 PREHARD28–32 HRCHARDENED TOOL STEEL60–62 HRC202383030240392505136069765832HRCHV10 HRC = 64 HV10 HRC = 184 HVEQUAL HRC STEPS STRETCH IN HV →ONE HARDNESS — TWO SCALESConversions from Mitutoyo Bulletin 2059(2) (steel) — approximate by definition. Spec ONE scale on the drawing; convert for reference only.
RockwellVickersBrinellApprox. tensile · steel
HRCHRBHVHBUTS ksiUTS MPa
68—940———
65—832739——
62—746688——
60—697654——
58—6536153382330
56—6135773132158
54—5775432922013
52—5445122731882
50—5134812551758
48—4844552381641
46—4584322211524
44—4344092081434
42—4123901941338
40—3923711821255
38—3723531711179
36—3543361611110
34—3363191521048
32—3183011461007
30—302286138951
28—286271131903
26—272258125862
24—260247119820
22—248237115793
20—238226110758
—98—228109752
—95—210100689
—92—19592634
—90—18589614
—86—16983572
—80—15072496
—75—13766455
—70—12561421
—60—107——
—50————

Key: bold = primary scales (HRC · HRB · HV)  ·  — = outside that scale’s usable range  ·  UTS = estimate from hardness, steel only

HRC — Rockwell C, diamond cone / 150 kgf. Hardened steel ≥ 20 HRC (tool steel, hardened 4140/4340, 17-4PH H900–H1075).

HRB — Rockwell B, 1/16″ ball / 100 kgf. Annealed steel, brass, aluminum bronze, hard plastics. Above ~100 HRB switch to HRC.

HV — Vickers, diamond pyramid / variable load. One scale from soft aluminum to carbide; thin coatings and case-depth work.

HB — Brinell, 10 mm ball / 3000 kgf for steel. Large indent averages non-uniform material — castings, forgings.

Approximate values from Mitutoyo Bulletin 2059(2), July 2017. HB uses the source's 3000 kgf / 10 mm ball column. No carbide-ball test equivalence is implied. HRB-region HV values are withheld: the source has a separate Knoop column and a combined HB/HV heading, not a separately identified Vickers test column. Tensile columns are approximate steel correlations, not test results or design allowables. A dash means unavailable in the source. Non-steel conversions require material-specific data. See thehardness conversion reference.

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Approximate conversions for steel from Mitutoyo Bulletin 2059(2) — verify against material-specific data for non-steel or design-critical work. · September 2026
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