Hardness Conversion Chart — HRC, HB, HV & Approximate Tensile Strength

ASTM E140 hardness conversions for non-austenitic steel: Rockwell C 20–65 to Brinell HB (3000 kgf), Vickers HV, and approximate tensile strength in ksi and MPa.

Updated August 18, 2026

These conversions are approximate and valid for steel only — specifically the non-austenitic steels of ASTM E140 Table 1. Hardness scales measure different things (indent depth under a diamond cone for Rockwell C, indent area under a ball for Brinell, under a pyramid for Vickers), so there is no exact formula between them; E140 tabulates empirical equivalences that hold for ordinary carbon and alloy steels and drift for austenitic stainless, aluminum, copper, and cemented carbides, which have their own tables.

Two honesty rules shape the blanks below. E140 marks Brinell values above HB 634 (HRC 60 and up) as beyond the range ASTM E10 validates for the test — a 3000 kgf ball barely dents material that hard — so those cells are dashed rather than extrapolated. And the tensile column is not part of E140 at all: it is the industry companion tabulation of approximate ultimate tensile strength, reproduced identically across steel-distributor charts, and it ends at HRC 59. It estimates what a tension test would read on through-hardened steel; use it for triage, never for design allowables.

Rockwell C to Brinell, Vickers & Approximate Tensile — Steel (ASTM E140)

HRCBrinell HB (3000 kgf)Vickers HVTensile ≈ (ksi)Tensile ≈ (MPa)
65—832——
64—800——
63—772——
62—746——
61—720——
60—697——
596346743512420
586156533382330
575956333252241
565776133132158
555605953012075
545435772922013
535255602831951
525125442731882
514965282641820
504815132551758
494694982461696
484554842381641
474434712291579
464324582211524
454214462151482
444094342081434
434004232011386
423904121941338
413814021881296
403713921821255
393623821771220
383533721711179
373443631661145
363363541611110
353273451561076
343193361521048
333113271491027
323013181461007
31294310141972
30286302138951
29279294135931
28271286131903
27264279128883
26258272125862
25253266123848
24247260119820
23243254117807
22237248115793
21231243——
20226238110758

Approximate, non-austenitic steel only. HB is the 10 mm carbide-ball 3000 kgf column; “—” = E140 marks the value beyond the validated Brinell range (HRC 60–65) or the published tensile column ends (HRC ≥ 60; HRC 21 unverified). MPa computed as ksi × 6.894757. E140’s standard-ball (HBS) column tracks the carbide values closely up to its own validity limit at HRC 48 and is not published above HRC 52.

Sources & Further Reading

  • ASTM E140-07 — Standard Hardness Conversion Tables for Metals, Table 1 (non-austenitic steel), adjudicated across the full-text reproduction, the Anderson Labs Rockwell-C-range table, and PGI Steel (three PGI outlier cells outvoted 2–1)
  • Approximate tensile strength: the integer-HRC companion tabulation reproduced cell-identically by Associated Steel, Benedict-Miller, and PGI Steel (not part of E140 itself; column ends at HRC 59)
  • MPa column computed as ksi × 6.894757 (exact NIST conversion), not transcribed — no E140-lineage chart publishes MPa at integer HRC

Frequently Asked Questions

Why is this chart marked approximate and steel only?

Because hardness scales measure different physical responses, the mapping between them depends on the material’s work-hardening behavior. ASTM E140 publishes separate tables for non-austenitic steel, austenitic stainless, brass, and other families — this chart is the steel table. For any other alloy the same HRC reading converts to noticeably different HB and HV values.

Why are the Brinell cells blank above HRC 59?

ASTM E10 caps the validated Brinell range near HB 634: beyond that, a 3000 kgf test barely indents the surface and readings become unreliable, so E140 prints those conversions in parentheses as out of range. This chart drops them entirely rather than lending false precision — measure hard materials with Rockwell C or Vickers instead.

How accurate is the tensile strength column?

It is a statistical correlation for through-hardened steel, typically within roughly ±5–10% — good enough to sanity-check a material certificate or size a rough design study, not to replace a tension test. A handy mid-range shortcut: tensile in psi runs about 485–490 × HB, so 300 HB steel pulls roughly 145 ksi (1000 MPa).

What do I use below HRC 20?

The Rockwell C scale itself loses validity below about HRC 20 — the diamond cone barely loads soft material. Softer steels are measured on the Rockwell B scale (1/16″ ball, 100 kgf); the E140 steel tables continue there, with HRB 100 corresponding to roughly HB 240, just below this chart’s bottom row.

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Hardness Conversion Chart — HRC, HB, HV & Approximate Tensile Strength — reuven.tools/reference/hardness-conversion — verified against: ASTM E140-07 — Standard Hardness Conversion Tables for Metals, Table 1 (non-austenitic steel), adjudicated across the full-text reproduction, the Anderson Labs Rockwell-C-range table, and PGI Steel (three PGI outlier cells outvoted 2–1); Approximate tensile strength: the integer-HRC companion tabulation reproduced cell-identically by Associated Steel, Benedict-Miller, and PGI Steel (not part of E140 itself; column ends at HRC 59); MPa column computed as ksi × 6.894757 (exact NIST conversion), not transcribed — no E140-lineage chart publishes MPa at integer HRC