Hardness Conversion Calculator
ASTM E140 standard conversions between Rockwell, Vickers, Brinell, and Shore scales with tensile strength approximation
Interactive Converter
HRC
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20 – 68
HRB
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60 – 100
HV (Vickers)
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111 – 940
HB (Brinell)
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111 – 627
HRA
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60.5 – 85.6
Shore D
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30 – 85
Approx. Tensile Strength (MPa)
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Approx. Tensile Strength (ksi)
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Visual Comparison Chart
Enter a hardness value above to see the visual comparison.
Common Material Hardness Reference
16 materials
| Material | Condition | HRC | HV | Typical Use |
|---|---|---|---|---|
| Mild Steel (EN3 / 1018) | Normalised | — | 120–160 | General fabrication |
| EN8 (1040) | Quenched & Tempered | 28–36 | 286–354 | Shafts, gears |
| EN19 (4140) | Q&T | 28–34 | 286–336 | High-stress components |
| EN24 (4340) | Q&T | 28–38 | 286–372 | Aircraft parts |
| EN31 (52100) | Hardened | 60–66 | 697–865 | Bearings |
| H13 Tool Steel | Hardened | 44–52 | 434–544 | Die casting dies |
| D2 Tool Steel | Hardened | 58–62 | 653–746 | Cutting tools |
| M2 HSS | Hardened | 63–66 | 772–865 | Drill bits |
| 304 Stainless | Annealed | — | 150–200 | Food equipment |
| 316 Stainless | Annealed | — | 150–200 | Marine, chemical |
| 17-4PH Stainless | H900 | 40–44 | 392–434 | Aerospace |
| Inconel 718 | Aged | 36–44 | 354–434 | Gas turbines |
| Ti-6Al-4V | STA | 36–40 | 354–392 | Aerospace |
| Cast Iron (Grey) | As-cast | — | 150–250 | Engine blocks |
| Brass | Annealed | — | 60–80 | Fittings |
| Aluminium 6061 | T6 | — | 95–110 | Structural |
Which Test to Use?
| Application | Recommended Test |
|---|---|
| Hardened steel (heat treated) | HRC (Rockwell C) |
| Soft/medium steel, copper, brass | HRB (Rockwell B) |
| Case-hardened layers, thin coatings | HV (Vickers micro) |
| Castings, forgings, thick sections | HB (Brinell) |
| Cemented carbides | HRA (Rockwell A) |
| Rubber, plastics, elastomers | Shore A / D |
| Weld hardness surveys (HAZ) | HV 10 (Vickers) |
| Nitrided / carburised case | HV 0.3 or HV 0.5 |
Minimum Specimen Thickness
The specimen must be thick enough that the indentation does not affect the opposite surface. General rule:
- Rockwell C: min 1.5 mm (10x indentation depth)
- Rockwell B: min 1.0 mm
- Brinell (3000 kgf): min 8x indentation depth (typ. 6–10 mm)
- Vickers HV 30: min 1.5x diagonal length
- Vickers HV 0.3 (micro): suitable for thin case layers > 0.1 mm
If specimen is too thin, readings will be artificially low. Use a lower load or different test.
Indenter Types & Loads
| Scale | Indenter | Load |
|---|---|---|
| HRA | Diamond cone (120°) | 60 kgf |
| HRB | 1/16" steel ball | 100 kgf |
| HRC | Diamond cone (120°) | 150 kgf |
| HV | Diamond pyramid (136°) | 1–120 kgf |
| HB | 10 mm TC ball | 3000 kgf (steel) |
| HB | 10 mm TC ball | 500 kgf (Al, Cu) |
TC = tungsten carbide. Steel balls no longer permitted per ISO 6506.
Microhardness vs. Macrohardness
Macrohardness (HRC, HRB, HB, HV 10–30):
- Bulk material properties
- Quality control, incoming inspection
- Large indentation — averages over microstructure
- Surface prep: ground or machined flat
Microhardness (HV 0.01–1, Knoop):
- Case depth profiles (carburised, nitrided)
- Individual phases & microstructural constituents
- Thin coatings, plating, weld HAZ traverses
- Requires polished surface (metallographic prep)
- Small indentation — sensitive to local variations