Free Engineering Tool
Hardness Converter
Convert between Rockwell HRC, Brinell HB, Vickers HV, and Rockwell HRB hardness scales. Based on ASTM E140 conversion data with linear interpolation.
Results
HRC Range (Hardened Steels)
| HRC | HV | HB | Rm (MPa) |
|---|---|---|---|
| 20 | 238 | 228 | ~787 |
| 25 | 255 | 243 | ~838 |
| 30 | 279 | 266 | ~918 |
| 35 | 331 | 311 | ~1073 |
| 40 | 392 | 360 | ~1242 |
| 45 | 458 | 421 | ~1452 |
| 50 | 542 | 484 | ~1670 |
| 55 | 595 | 544 | ~1877 |
| 60 | 697 | — | — |
| 65 | 832 | — | — |
HRB Range (Softer Steels)
| HRB | HV | HB | Rm (MPa) |
|---|---|---|---|
| 60 | 107 | 105 | ~362 |
| 70 | 120 | 118 | ~407 |
| 80 | 141 | 138 | ~476 |
| 90 | 171 | 166 | ~573 |
| 100 | 210 | 202 | ~697 |
ℹ️ Note: Values between table entries are calculated using linear interpolation. HB values above HRC 55 are typically not measured (material too hard for ball indenter). Tensile strength estimates apply to carbon and alloy steels only.
Rockwell Hardness (HRC / HRB)
The Rockwell test measures the depth of penetration under a large load compared to a preload. It is fast, easy, and widely used in production.
- HRC — Diamond cone (Brale) indenter, 150 kgf major load. Range: 20–70 HRC. For hardened steels.
- HRB — 1/16″ steel ball, 100 kgf major load. Range: 20–100 HRB. For softer steels, brass, aluminum.
Vickers Hardness (HV)
Uses a diamond pyramid indenter with variable load (1–120 kgf). Measures the diagonal of the indentation. Works for all hardness ranges from very soft to very hard.
Brinell Hardness (HB)
Uses a 10 mm tungsten carbide ball with 3000 kgf load (for steel). Measures the diameter of the indentation. Best for coarse-grained materials like castings.
Tensile Strength Approximation
⚠️ Important: The Rm ≈ 3.45 × HB relationship is approximate and only valid for carbon and alloy steels in the range ~100–400 HB. Do not use for stainless steels, cast irons, non-ferrous metals, or hardened steels above ~55 HRC.
Practical Example
Given: Measured hardness = 45 HRC
From ASTM E140 table: HRC 45 ≈ HV 458 ≈ HB 421
Estimated tensile strength: Rm ≈ 3.45 × 421 = ~1452 MPa
Each scale uses a different indenter and load:
- HRC (Rockwell C) — Diamond cone, 150 kgf. For hardened steels (20–70 HRC).
- HRB (Rockwell B) — 1/16" steel ball, 100 kgf. For softer materials (20–100 HRB).
- HV (Vickers) — Diamond pyramid, variable load. Universal range, very precise.
- HB (Brinell) — 10 mm carbide ball, 3000 kgf. For castings, larger test areas.
General guidance:
- HRC — Hardened and tempered steels, tool steels, case-hardened parts
- HRB — Annealed steels, brass, aluminum, softer metals
- HV — Thin sheets, coatings, micro-hardness, wide range of materials
- HB — Castings, forgings, raw stock, weld HAZ testing
When in doubt, use HRC for hardened steels and HV for everything else.
Different hardness tests measure different physical properties:
- Rockwell measures depth of penetration
- Vickers measures area of indentation
- Brinell measures diameter of indentation
Since these are fundamentally different measurements, the relationships between them are empirical (based on testing), not mathematical. Results vary by material type, microstructure, and heat treatment condition.
ASTM E140 provides accepted approximate conversions based on extensive testing of carbon and alloy steels.
For carbon and alloy steels, the approximate relationship is:
- Rm (MPa) ≈ 3.45 × HB
- Rm (psi) ≈ 500 × HB
This is valid for the range of approximately 100–400 HB. Above ~55 HRC, this relationship breaks down as materials become brittle.
Do not use this for stainless steels, cast irons, non-ferrous metals, or materials with unusual microstructures.
Rockwell (ASTM E18): Apply preload (10 kgf), then major load (60/100/150 kgf). Measure depth increase. Quick (~10s), portable, minimal surface preparation.
Vickers (ASTM E92/E384): Force a diamond pyramid into the surface. Measure both diagonals under microscope. Very precise, works for micro-hardness (HV 0.01) to macro (HV 120).
Brinell (ASTM E10): Press a 10 mm ball into the surface with 3000 kgf (for steel). Measure indentation diameter. Averages over a large area — ideal for heterogeneous materials like castings.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
Professional field balancing instruments and software. Used in 50+ countries.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
