Hardness Conversion Calculator
Rockwell ⇄ Brinell Converter
Convert between Rockwell C (HRC), typically reported for heat-treated or hardened steel, Rockwell B (HRB), typically reported for softer or annealed steel, and Brinell (HBW). Based on ASTM E140 conversion tables for non-austenitic carbon, alloy, and tool steels.
Convert From
HRC
Valid range: 20–68 HRC
Rockwell B
—
Brinell (HBW)
—
Soft / Annealed
Hardened / Quenched
Which Scale Applies?
Each hardness scale only applies reliably over part of the total hardness range. Using a scale near or beyond its effective range can increase conversion error.
Rockwell C · HRC
Effective Range
20–70 HRC (diamond cone, 150 kgf)
Use For
Hardened, quenched and tempered, case-hardened steel, and tool steel.
Avoid When
Below 20 HRC. The cone cannot get a reliable reading on material
this soft. Use HRB instead.
Rockwell B · HRB
Effective Range
0–100 HRB, most reliable below approximately 90
(1/16" ball, 100 kgf).
Use For
Annealed, normalized, or cold-worked steel and low- or
medium-carbon grades.
Avoid When
Above 100 HRB. The scale saturates and loses resolution.
Material near the top of this range may be better tested using HRC.
Brinell · HBW
Effective Range
Approximately 90–650 HBW practical
(10 mm ball, 3000 kgf).
Use For
Castings, forgings, coarse or non-uniform microstructures, and
materials spanning both Rockwell conditions.
Avoid When
Above approximately 650 HBW. The carbide ball itself begins
deforming before steel at these hardness levels.
Rule of thumb:
if a Rockwell B reading would land above 100, or a Rockwell C reading
would land below 20, the material is on the wrong scale. Re-test using
the other scale instead of relying on an extrapolated value. The
calculator will warn you when this occurs.
Full Reference Table
ASTM E140 · Non-Austenitic Steels
| Rockwell B (HRB) | Rockwell C (HRC) | Brinell (HBW 10/3000) | Vickers (HV) |
|---|