Engineering Reference

Hardness Conversion Calculator

Convert between Rockwell C, Rockwell B, Brinell and Vickers using the ASTM E140 relationships for steel.

Page last changed 2026-10-19 · based on n/a — standard engineering relationships, no single governing revision

Quick Answer

Hardness scales are not related by a single formula — conversions are empirical. For rough work in the mid range, Vickers ≈ 10 × Rockwell C and Brinell ≈ Vickers ÷ 1.05.

Hardness Converter

The Formulas Used

HV ≈ 10 × HRC
HB ≈ HV ÷ 1.05 (mid range)
tensile ≈ HB × 515 (HB ≤ 175)  or  HB × 490 (HB > 175)

These Are Approximations

The relationships above are useful for sanity checks in the mid range, roughly 20–55 HRC. They are not the standard's conversion table. For a value that matters, use the tabulated conversion on the hardness conversion chart, which follows ASTM E140.

Conversions are also material-class specific. The relationships here are for steel; aluminium, copper alloys and cast iron each need their own table, and using steel conversions on them gives large errors.

Why Conversion Is Empirical

Each test measures a different geometric response to indentation — Rockwell measures depth, Brinell measures the diameter of a spherical impression, Vickers measures the diagonal of a pyramidal one. Because the geometries differ, the scales respond differently to the same material, and the relationship between them is a fitted curve through paired measurements rather than a physical law.

Frequently Asked Questions

How do I convert Rockwell C to Brinell?
For a rough estimate, HB ≈ 10 × HRC ÷ 1.05. So 45 HRC is about 429 HB, against a tabulated value of 421. For anything that matters, use the ASTM E140 conversion table.
Is Rockwell C the same as Vickers divided by 10?
Approximately, in the mid range. 45 HRC is 446 HV and 446 ÷ 10 = 44.6. The relationship drifts at both ends of the range.
How do I convert hardness to tensile strength?
For steel, tensile (psi) ≈ Brinell × 515 below HB 175, and × 490 above. The scatter is roughly ±10%, so treat the result as an estimate.
Does hardness conversion work for aluminium?
No. The relationships on this page are for steel. Aluminium, copper alloys and cast iron need their own conversion tables, because they work-harden and respond to indentation differently.
Which hardness scale should I specify?
Match the scale to the range and the part: Rockwell C for hardened steel (20–70 HRC), Rockwell B for soft metals, Brinell for castings, and Vickers for thin or case-hardened sections. Do not specify one scale and accept a converted value from another.

Related

Value Sources

References and calculation methods used for this page are listed below. Numbered markers connect table columns where present. A reference listing does not itself establish that every value has been independently checked.

#SourceTypeRevision / method
[1]ASTM E140 — Hardness Conversion TablesreferenceASTM E140-12b — source
[2]Values computed in your browserderivedEvaluated locally from the formulas shown on the page. No data leaves the device.

Data Sources

StandardRevisionWhat it covers on this page
Formulas as shown on this pagen/a — standard engineering relationships, no single governing revisionevery value this calculator produces

Verification scope

No page-specific independent source review is recorded here. The listed references and formulas explain the basis of the compilation; automated consistency checks do not verify the original sources or establish product conformity.

Derived values — the following values on this page are calculated, not taken directly from the standard:

ValueHow it is derived
All outputsComputed in the browser from the formulas above. No data leaves the device.

Outputs are computed from the formulas shown. Verify against the governing standard for design or acceptance work.

Accuracy and use. Use the source notes and recorded verification scope above to assess each value. Calculated values follow the stated derivations; compilation values may lack a confirmed original document or product condition. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

Cite This Page

Read the source notes, calculation methods and verification scope above before reusing a value. To cite this page: