› Hardness Conversion Simulator Back
Materials Testing Simulator

Hardness Conversion Simulator — HB ↔ HRC ↔ HV ↔ HK ↔ HS

Quick answer
Hardness values can be converted using HV≈1.05·HB+5 (ASTM E140 / JIS Z2244). For Rockwell, HRC≈−10.9+0.160·HV−8.24×10⁻⁵·HV², and for steel the tensile strength is roughly σB[MPa]≈3.2·HV.

Map Brinell HB to Vickers HV, Rockwell HRC, Knoop HK, Shore HS and tensile strength sigma_B in real time using ASTM E140 / JIS Z 2244 correlations, with material-class corrections for steel, stainless, aluminium and copper alloys.

Parameters
Brinell hardness HB
HB
Material mode
—
Test load gauge
—
Standard
—

Material: 0 = steel (baseline), 1 = stainless, 2 = aluminium alloy, 3 = copper alloy. Gauge: 0 = standard, 1 = low load (micro-hardness). Standard: 0 = ASTM E140, 1 = JIS Z 2244. HRC reads '—' for HB ≤ 250.

While paused, move the sliders to update the result instantly.

Results
—
Vickers HV
—
Brinell HB
—
Rockwell C HRC
—
Tensile strength σ_B (est.)
Indentation & scale conversion (auto-sweep)

The indenter presses the material; the indent (d) shrinks as hardness rises. The marker sweeps HB while HV, HB, HRC and tensile strength σ_B respond together. Drag the HB slider to pause.

Theory & Key Formulas

Hardness-scale conversions are not first-principles physics but empirical regressions based on ASTM E140 and JIS tables. The simplified steel-baseline relations are:

Brinell HB → Vickers HV (linear approximation):

$$\mathrm{HV} \approx 1.05\,\mathrm{HB} + 5$$

HV → Rockwell HRC (the tool interpolates an ASTM E140-based table piecewise-linearly; the fit below is approximate, valid for HV ≥ 240):

$$\mathrm{HRC} \approx -10.9 + 0.160\,\mathrm{HV} - 8.24\times10^{-5}\,\mathrm{HV}^2$$

HV → Knoop HK, HV → Shore HS, HB → tensile strength σ_B:

$$\mathrm{HK} \approx 0.985\,\mathrm{HV},\qquad \mathrm{HS} \approx 0.05\,\mathrm{HV} + 8,\qquad \sigma_B\,[\mathrm{MPa}] \approx 3.5\,\mathrm{HB}$$

For HB from indent diameter see brinell-hardness.html. Related simulators: belt-friction.html, pelton-turbine.html, boids-flocking.html.

What is the hardness conversion simulator?

🙋
The drawing says "200 HB minimum" but the only hardness tester on the shop floor is a Rockwell. Can I just convert?
🎓
You can, ASTM E140 and the JIS tables give you the correlation. Set HB = 200 here and you'll see HV ≈ 215 and sigma_B ≈ 700 MPa pop out. But HRC shows '—'. That's not a bug — HB 200 is below the meaningful Rockwell C range, so the reading would be unreliable.
🙋
Why is HRC unreliable there? It's still a hardness number.
🎓
Rockwell C uses a 150 kgf major load on a diamond cone, designed for hardened steel. Below about HRC 20 (HB 235, HV 240) the indenter sits near the bottom of the dial and the reading scatters. So softer materials are measured on HRB (steel ball + 100 kgf) instead. Push HB to 400 in the tool: HRC ≈ 43 — that's quenched and tempered S45C territory.
🙋
Cool — when I move the slider the curves move too. Red HV, blue HRC×10, green HK, purple sigma_B/10 all on the same chart.
🎓
Right, that chart visualises the inter-scale relations at a glance. HV grows roughly linearly with HB (slope 1.05), HK overlays HV but slightly lower (HK ≈ 0.985·HV), HRC is non-linear and only takes off above HV 240, and sigma_B is about 3.5·HB — "200 HB → 700 MPa" is the rule of thumb you can use to estimate tensile strength non-destructively for steel.
🙋
When I switch the material to aluminium the sigma_B drops. Is that conversion really correct?
🎓
The sigma_B/HB coefficient depends on the material class. Steel ≈ 3.5, aluminium alloys ≈ 3.4, austenitic stainless ≈ 3.7 (strong strain hardening), copper alloys ≈ 4.0. These are empirical corrections, not material constants — so the tool values are first-order estimates with about ±10% scatter. Always run a primary test before any acceptance decision.

FAQ

Both measure something close to the mean contact pressure per unit projected area. Brinell divides load by the spherical cap area and Vickers divides by the lateral pyramid area, but Tabor's relation p_m ≈ 3·σ_y holds for both. The near-linear approximation HV ≈ 1.05·HB + 5 follows. At high hardness (HB above 500) HV reads higher, drifting toward HV ≈ 1.1·HB.
Strictly only for steel (carbon and low-alloy). ASTM E140 dedicates its primary table to steel; non-ferrous metals (nickel, copper, aluminium alloys) use auxiliary tables B–H with narrower validity ranges. The tool applies a simple material-class correction, but you should treat non-ferrous conversions as order-of-magnitude estimates and run the material-specific direct test before accepting parts.
Shore (scleroscope) is a dynamic rebound test: a diamond-tipped hammer (Shore C) or steel ball (Shore D) is dropped onto the specimen and the rebound height is the hardness. Rebound depends on elastic recovery, while HB/HV/HRC measure plastic indentation. The empirical HS ≈ 0.05·HV + 8 holds with about ±15% scatter, so it is only useful where that tolerance is acceptable, such as field checks on large rolls.
ASTM E140 "Standard Hardness Conversion Tables for Metals" is sold via the ASTM International website. Table 1 (steel) is the most widely referenced and links Brinell HB (10 mm ball, 3000 kgf), Vickers HV, Rockwell HRC/HRB/HRA, HR15N and several superficial scales in a single row. In Japan the equivalent tables appear in JIS B 7724 (Vickers verification) and JIS G 0202 (steel terminology), and accredited test laboratories quote values per these standards.

Real-world applications

Bridging material specifications and shop-floor measurements: Material standards usually state HBW, while most field instruments read HRC, HRB or portable HV. Knowing that "S45C Q&T HBW 217–277" corresponds to HRC 22–29 lets the inspector accept or reject a part on the spot without waiting for a re-test.

Non-destructive tensile strength estimation: When a tensile test is impractical (machined parts, castings, weld zones) the sigma_B ≈ 3.5·HB [MPa] rule gives a fast estimate. HB 200 ⇒ ~700 MPa, HB 300 ⇒ ~1050 MPa. It is widely used in first-pass strength sizing and to characterise the heat-affected zone (HAZ) of welds.

Quality traceability across process steps: A part can be tested on different scales at different production stages — HB before heat treatment, HRC after. Converting everything to a common HB-equivalent makes the lifetime hardness history coherent and easier to audit.

Reconciling imported material certificates: US mills typically report HRC/HRB, EU mills HV, JP mills HB/HV, CN mills HB/HRC. ASTM E140 and JIS Z 2244 are the common language that lets you map a certificate value into the in-house reference scale.

Common misconceptions and pitfalls

The single biggest mistake is to treat a converted value as a measured value. An HRC computed from an HB reading is not the HRC you would obtain by direct Rockwell measurement; the difference is typically ±2 units. For acceptance testing under any standard you must run the specified test directly. "Converted HRC 25, therefore accept" will not survive an audit.

The second pitfall is using the conversion outside its validity range. HRC needs HV ≥ 240 (HB ≥ 235); below that, use HRB. This tool prints '—' for HRC when HB ≤ 250 to prevent that misuse. At the high end, HRC tops out at about 68 (HV 940); harder materials should be reported in HV or HRA (120 kgf diamond cone).

The third pitfall is applying sigma_B ≈ 3.5·HB to non-ferrous metals. Aluminium alloys land near 3.4, pure cold-worked aluminium can drop to 2.8, copper alloys climb to 4.0. Austenitic stainless steels strain-harden strongly so a high surface hardness does not always correspond to a high tensile strength, and the coefficient scatters between 3.6 and 3.8. Always pick the correct material class or measure sigma_B directly. See brinell-hardness.html for the HB calculation from indent diameter, and pelton-turbine.html, boids-flocking.html, belt-friction.html for other interactive engineering tools.

Related Tools

Stress Strain Curve Interactive tool to generate and compare stress-strain curves for metals, rubber, and concr... Yield Criteria Visualize and compare von Mises, Tresca, and Drucker-Prager yield criteria in real-time. Ca... Tresca vs Mises Yield Criteria Simulator — Principal Stress Space Comparison Compare the Tresca and von Mises yield criteria in principal stress space. Tune sigma1, sig...

How to Use

  1. Set the Brinell hardness HB with the slider (range 100–600 HB; e.g., 450 HB for quenched-and-tempered steel).
  2. Set the material mode slider: 0 = steel (baseline), 1 = stainless, 2 = aluminium alloy, 3 = copper alloy. Non-steel modes apply a small material correction to the converted values.
  3. Set the test load gauge: 0 = standard, 1 = low load (micro-hardness; raises the HV reading by about 3%).
  4. Set the standard: 0 = ASTM E140, 1 = JIS Z 2244. HV, HRC, HK, HS and the estimated tensile strength σ_B update in real time (HRC shows "—" below about HB 250).

Worked Example

A normalized structural steel shaft measured at 280 HB (10 mm ball, 3000 kgf load per ASTM E10). The simulator converts: HV ≈ 299, HRC ≈ 29.7, estimated tensile strength σ_B ≈ 980 MPa, HK ≈ 295. Switching the material mode to stainless (1) at the same HB applies the reading correction, giving HV ≈ 305 and σ_B ≈ 1036 MPa. In this tool Knoop hardness is taken as HK ≈ 0.985·HV, slightly below Vickers; all conversions are empirical, so allow roughly ±10% scatter.

Practical Notes

  1. ASTM E140 conversion tables have ±5% uncertainty; use actual tensile testing for critical applications (e.g., pressure vessels, fasteners).
  2. HRC applies only to hardened steel (typically 20–65 HRC); soft aluminium alloys require HV or HB instead.
  3. Load-dependent scatter: 282 HV at 10 kgf differs from 282 HV at 50 kgf; always specify load class in reports.
  4. Rockwell C indenter (120° cone) cannot reliably convert materials below 20 HRC; use Rockwell B or Vickers for softer grades.

Standards & Assumptions

Standard/formula: Cross-scale hardness conversion follows ASTM E140 (≈ ISO 18265) tables — empirical regressions, not physical laws. Tool (steel baseline): HV ≈ 1.05·HB + 5; HV→HRC by piecewise-linear interpolation of an ASTM E140-style anchor table (valid HV ≥ 240); HK ≈ 0.985·HV; HS ≈ 0.05·HV + 8; tensile strength σ_B[MPa] ≈ 3.5·HB.

Assumptions: steel is the baseline; stainless, aluminium and copper alloys apply small correction factors. The HRC table reproduces ASTM E140 reference points (e.g. HV300→29.8, HV600→55.2 HRC); the σ_B coefficient 3.5 sits in the classic 3.3–3.6 band (0.35·HB kgf/mm²).

Scope & limits: conversions are approximate; real values scatter by a few HRC with material, heat treatment and test load (E140 itself carries spread). HRC is undefined for HV < 240. Confirm critical values by direct hardness testing.