Hardness Converter
Convert between Rockwell HRC/HRB, Brinell HB, Vickers HV, and Shore D hardness scales. Instant interpolated conversion.
Introduction
Hardness values arrive from suppliers, drawings, and test reports in different scales — Rockwell C for hardened tool steel, Rockwell B for soft steel and non-ferrous alloys, Brinell for castings and forgings, Vickers for thin cases and lab work. The Hardness Converter translates between HRC, HRB, HB, HV and Shore D in one step and also estimates the approximate tensile strength of steel at that hardness. Instead of flipping through printed ASTM E140 tables and interpolating by hand, you enter one value and read the full row of equivalents, which is exactly what you need when an incoming-inspection report uses a different scale than the drawing.
How it Works
The converter is built on a standard steel conversion table keyed to ASTM E140 values, spanning HRC 68 down through HRB 50. An exact table hit returns the published equivalents directly; any value between rows is linearly interpolated from the two bracketing rows, which keeps results faithful to the table rather than to a fitted curve. Tensile strength is read from the same row — for example HRC 40 corresponds to roughly HB 392, HV 409, and 1310 MPa — and the MPa figure is multiplied by 0.145038 to display ksi for imperial drawings.
Usage Scenarios
- Receiving inspection: the heat-treat certificate states HV 540 but the drawing calls for HRC 48–52 — converting confirms HV 540 ≈ HRC 50, inside the window.
- Selecting cutting parameters: a 4140 shaft quoted at HB 302 converts to about HRC 30, which tells you whether it machines as pre-hard or needs to be treated as hardened steel.
- Estimating tensile strength of an unknown steel from a portable hardness reading when no mill cert is available.
- Comparing a Shore D reading on a hard polymer wheel against the metallic scales it sits alongside in a mixed-material assembly spec.
- Writing a deviation request: showing numerically that HRB 95 and HB 238 describe effectively the same material condition.
FAQ
How accurate are the conversions?
Conversions follow published steel correlation tables and are approximate by nature — scale geometry and material differ. For acceptance decisions on critical parts, test in the scale specified on the drawing.
Why does tensile strength appear with the hardness result?
For steels, hardness correlates strongly with ultimate tensile strength, so the table carries an approximate UTS column. The ksi figure is derived by multiplying MPa by 0.145038.
Can I convert hardness for aluminum or copper alloys?
The table is steel-based. Non-ferrous alloys follow different correlations, so HRB-to-HB conversions for aluminum, brass, or bronze require their own ASTM E140 tables.
What happens if I enter a value between two table rows?
The converter linearly interpolates between the bracketing rows of the table, so intermediate inputs return proportionally intermediate equivalents instead of snapping to the nearest published row.