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.

Hardness Conversion Calculator

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

Data verified 2026-09-29 · 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

Rockwell C

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.

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

#	Source	Type	Revision / method
[1]	ASME B1.1 — Unified Inch Screw Threads	standard	ASME B1.1-2019 — source
[2]	ASTM A615 — Deformed steel bars for concrete reinforcement	standard	ASTM A615/A615M-20 — source
[3]	ASTM E140 — Hardness Conversion Tables	standard	ASTM E140-12b — source
[4]	Values computed in your browser	derived	Evaluated locally from the formulas shown on the page. No data leaves the device.
[5]	ISO 4287 — Surface texture: Profile method	standard	ISO 4287:1997 — source
[6]	ISO 68-1 — Basic profile	standard	ISO 68-1:2023 — source
[7]	NFPA 70 NEC Table 310.16	standard	NEC 2023 (NFPA 70-2023) — source

Data Sources

Standard	Revision	What it covers on this page
Formulas as shown on this page	n/a — standard engineering relationships, no single governing revision	every value this calculator produces

Cross-checked against:

Formulas verified against the corresponding reference chart on this site, so the calculator and the published tables agree

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

Value	How it is derived
All outputs	Computed 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. The values on this page are compiled from the published standards and cross-checked sources listed above. Where values are derived, the derivation is stated. 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

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Plain text

Engineering Reference. "Hardness Conversion Calculator." https://refmanual.com/calculators/hardness-converter/ (accessed 2026-09-29). Data from Formulas as shown on this page, n/a — standard engineering relationships, no single governing revision.

BibTeX

@misc{hardness-converter,
  title        = {Hardness Conversion Calculator},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/calculators/hardness-converter/}},
  note         = {Accessed: 2026-09-29},
  source       = {Formulas as shown on this page, n/a — standard engineering relationships, no single governing revision}
}

RIS (EndNote, Zotero, Mendeley)

TY  - ELEC
TI  - Hardness Conversion Calculator
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/calculators/hardness-converter/
PY  - 2026
DA  - 2026-09-29
N1  - Source: Formulas as shown on this page, n/a — standard engineering relationships, no single governing revision
ER  -

Each row in the tables above also has a permanent link — hover a row and use the # link to cite a single value rather than the whole page.