Convert HRC to HBW (Rockwell C to Brinell) for steel, or Brinell back to Rockwell C, using a published steel hardness table covering 26–57 HRC.
HRC to HBW Formula
The calculator linearly interpolates between adjacent HRC/HBW pairs from Uddeholm’s Heat Treatment of Uddeholm Tool Steels, printed page 18, which states an EN-ISO 18265:2013 basis. Interpolation is this calculator’s estimate method; it is not a universal polynomial or an ASTM certification:
For reverse conversion, swap the axes of the same paired table. Decimal-place selection affects display only. No tensile-strength estimate is calculated by this widget:
- HRC — Rockwell C hardness, 150 kgf load, diamond cone indenter
- HBW — Brinell hardness, 3000 kgf load, 10 mm tungsten carbide ball
- UTS — ultimate tensile strength; the table below gives source comparison values only, not a widget output
This implementation supports 26–57 HRC and 259–603 HBW, the paired range in the selected source table, with no extrapolation. Applicability depends on the exact material and heat treatment. Converted hardness is an indication, not a substitute for a standard test; tensile-strength comparisons are particularly uncertain. ISO 18265 scope and cautions.
Reference Tables
Selected published comparison values from Uddeholm’s hardness table, printed page 18. HV refers to the source’s 30 kg test; MPa equals N/mm². The original source gives UTS in kp/mm², not ksi; the last column below converts its MPa values to approximate ksi.
| HRC | HBW | HV | UTS (MPa) | UTS (ksi) |
|---|---|---|---|---|
| 26 | 259 | 273 | 873 | 127 |
| 30 | 287 | 302 | 970 | 141 |
| 35 | 328 | 345 | 1111 | 161 |
| 40 | 373 | 392 | 1262 | 183 |
| 45 | 424 | 446 | 1425 | 207 |
| 50 | 488 | 513 | 1675 | 243 |
| 55 | 566 | 596 | 1979 | 287 |
| 57 | 603 | 634 | 2121 | 308 |
Source coverage used by this calculator:
| Condition | HRC | HBW |
|---|---|---|
| Lower supported endpoint | 26 | 259 |
| Upper supported endpoint | 57 | 603 |
| Outside source coverage | No extrapolation | No extrapolation |
Worked Example
A steel shaft is specified at 45 HRC. Find the approximate Brinell comparison in the selected table.
- Choose Brinell HBW from Rockwell C, enter 45 HRC, then Calculate. The source pair gives approximately 424 HBW.
- For 45.5 HRC, interpolate halfway between 45 HRC / 424 HBW and 46 HRC / 436 HBW: approximately 430 HBW. The source table’s 1425 MPa UTS comparison at 45 HRC is not a tensile test.
Why the result may differ from another table. Conversion depends on the material, test method and chosen empirical table. Rounding and interpolation also affect displayed values. Use a direct test when the specification calls for one; this calculator does not promise a universal error bound.
Soft material and other test scales. The selected source describes Rockwell C for hardened steel and Brinell for soft annealed or prehardened steel. Consult the applicable test standard and material specification; a missing conversion here does not establish which test to use.
