Hardness Conversion Calculator
Drawings specify hardness on whichever scale the designer preferred; your test equipment measures on whichever scale you own. This calculator bridges the two — with the important caveat that a conversion is never a substitute for testing on the specified scale.
Hardness converts approximately between Brinell, Rockwell C and Vickers using the ASTM E140 relationships. For steel, tensile strength in MPa is roughly 3.4 times the Brinell number. Where a drawing specifies a scale, the part must be tested on that scale rather than converted onto it.
- Standard
- ASTM E140 relationships
- Brinell range
- ≈150 – 650 HB
- Rockwell C range
- ≈20 – 65 HRC
- Vickers
- Full range
- Tensile estimate
- ≈3.4 × HB in MPa
- Validity
- Common steels, approximate
Hardness Conversion Calculator at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Standard: ASTM E140 relationships
- Brinell range: ≈150 – 650 HB
- Rockwell C range: ≈20 – 65 HRC
- Vickers: Full range
- Tensile estimate: ≈3.4 × HB in MPa
- Validity: Common steels, approximate
Hardness Conversion Calculator
Conversions follow the ASTM E140 relationships for steel. They are indicative only: where a drawing specifies a scale, the part must be tested on that scale, not converted onto it.
How the Scales Differ
Brinell presses a large ball and measures the indentation diameter, averaging over a wide area — good for coarse structures like castings and forgings. Rockwell C uses a diamond cone and measures depth, fast and suited to hardened steel. Vickers uses a diamond pyramid and works across the whole range including thin cases.
- Brinell: large ball, wide average
- Rockwell C: diamond cone, depth measured
- Vickers: diamond pyramid, full range
- Each suits different材 conditions
Why Conversions Are Approximate
The relationships in ASTM E140 are empirical, derived from measurements on specific materials. They hold reasonably for common steels and drift for others. Converting a converted value compounds the error further.
When You Must Test on the Specified Scale
If a drawing states 58–62 HRC, the part must be tested on Rockwell C. Reporting a Brinell measurement converted to HRC is not compliance, and an auditor will treat it as a nonconformity.
Topics covered on this page
- hardness conversion calculator
- HRC to HB conversion
- Brinell to Rockwell chart
- Vickers hardness conversion steel
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
How do I convert HRC to Brinell?
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Use the ASTM E140 relationships, as this calculator does. The conversion is approximate and valid mainly for common steels.
Can I report a converted hardness value?
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Not where a drawing specifies a scale. The part must be tested on the scale named, or the result is a nonconformity.
Why is Brinell used for forgings?
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Its large indenter averages over a wide area, which suits the coarser structures found in forgings and castings.
How does hardness relate to tensile strength?
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For steel, tensile strength in MPa is roughly 3.4 times the Brinell number — useful as an estimate, not as a substitute for tensile testing.