Rockwell Hardness Conversion Calculator — HRC to HV, HB, UTS
Convert a Rockwell C (HRC) reading to Vickers (HV), Brinell (HB) and approximate tensile strength (MPa / ksi) using linearly-interpolated ASTM E140 Table 2 values for non-austenitic steels. Brinell is listed only up to HRC 50 because standard 10 mm / 3 000 kgf indenters cannot reliably test harder material.
Approximate conversion per ASTM E140 — non-austenitic steel
- 1
ASTM E140 bracket rows
HRC 35 → HV 345 ; HRC 40 → HV 392Two nearest table rows that bracket the input HRC. - 2
Interpolation fraction t
(40 − 35) ÷ (40 − 35) = 1 - 3
Vickers HV = HV₀ + t × (HV₁ − HV₀)
345 + 1 × (392 − 345) = 392
How does this calculator work?
Enter HRC (Rockwell C scale, range 20–68) and get Vickers HV, Brinell HB (up to HRC 50), and estimated tensile strength using ASTM E140 Table 2 interpolation for non-austenitic steels. UTS ≈ 3.45 × HB (MPa) for carbon/alloy steels; all values are approximate — measure directly for design-critical applications.
Formula
How this is calculated
Rockwell, Vickers and Brinell hardness scales all measure a material's resistance to indentation, but with different indenters and loads. Because no universal analytical formula converts between them, ASTM E140 (last revised 2019) provides empirically derived conversion tables for specific material classes. This calculator interpolates Table 2 — non-austenitic steels — which covers HRC 20 to 68.
Vickers hardness (HV) uses a square-pyramidal diamond pressed in with a small load, and the result scales nearly linearly with yield strength for steel. Brinell (HB) uses a 10 mm tungsten-carbide ball at 3 000 kgf; above roughly HRC 50 (HV ≈ 513, HB ≈ 481) the steel is too hard for a reliable Brinell impression and the scale is considered invalid — the calculator shows "> scale limit" for those inputs.
The tensile strength estimate UTS ≈ 3.45 × HB is a well-established empirical rule for carbon and alloy steels (derived from the Tabor relationship, first published 1951, widely verified). Above the Brinell limit the calculator falls back to UTS ≈ 3.28 × HV, which is a rougher approximation. Both are only indicative — actual UTS can vary ±10% depending on composition, heat treatment and microstructure. Always measure tensile strength directly for engineering design.
Frequently asked questions
At HRC ≈ 50 the material hardness approaches 500 HB. Above this level the tungsten-carbide ball itself can deform during indentation, producing unreliable results. ASTM E140 does not list Brinell equivalents above this point. Vickers and Knoop scales (diamond indenters) remain valid up to and beyond HRC 68.
No. ASTM E140 Table 2 is specifically for non-austenitic steels (carbon and low-alloy). Stainless steels, tool steels, cast irons, aluminium and copper alloys each have separate conversion tables (Tables 3–7). Using Table 2 for other materials can give errors of 5–15% or more.
The rule UTS ≈ 3.45 × HB is accurate to roughly ±5% for medium-carbon and alloy steels that are not cold-worked or precipitation-hardened. For case-hardened parts the surface HRC is much higher than the core, so the measured hardness over-predicts bulk tensile strength. The estimate should be used for screening only, not as a substitute for tensile testing.
Also known as
TG we-Calculate Editorial Team. (2026). Rockwell Hardness Conversion Calculator — HRC to HV, HB, UTS [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/rockwell-hardness-conversion-calculator
TG we-Calculate Editorial Team. "Rockwell Hardness Conversion Calculator — HRC to HV, HB, UTS." TG we-Calculate. 2026. https://we-calculate.com/calculator/rockwell-hardness-conversion-calculator.
TG we-Calculate Editorial Team, "Rockwell Hardness Conversion Calculator — HRC to HV, HB, UTS," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/rockwell-hardness-conversion-calculator
@misc{wecalculate_rockwell_hardness_conversion_calculator, title = {Rockwell Hardness Conversion Calculator — HRC to HV, HB, UTS}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/rockwell-hardness-conversion-calculator}}, year = {2026}, note = {TG we-Calculate} }
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