Convert between Rockwell (HRC, HRB), Brinell (HB), Vickers (HV) and estimate tensile strength (MPa & psi). Enhanced with material classification, exact table mode, and tolerance bands for engineering precision.
Hardness is a material’s resistance to localized plastic deformation. Different test methods (Rockwell, Brinell, Vickers) use distinct indenters and loads, making direct comparison non‑trivial. Conversion standards like ASTM E140-12 and ISO 18265 provide empirical correlations, especially for steels. Engineers rely on these conversions to translate legacy data, specify heat treatment quality, and estimate tensile strength without destructive testing. Our calculator implements industry‑accepted approximation formulas derived from these standards, suitable for carbon steels, alloy steels, and cast irons within typical ranges.
Core conversion logic (for steel, HRC 20–68):
HB ≈ 8.5 × HRC + 40 | HV ≈ 9.2 × HRC + 210 | UTS (MPa) ≈ 3.45 × HB
* Adjusted piecewise for HRB, HV, and mutual consistency using ASTM E140-12 tables. For HRB range (60–100) separate correlation to HB and HV is applied. Results are indicative for engineering estimation.
Our tool uses a robust internal mapping based on recognized data points from SAE and ASM handbooks. When you select a source scale and input a value, the engine converts to intermediate HB (Brinell) as a pivot, then distributes to other scales with high‑order interpolation. For HRC values below 20 or above 68, the converter shows a caution because conversions become less reliable. For Rockwell B (HRB), we use distinct polynomial fits to match Brinell range 100–240. The tensile strength estimation uses the empirical relation UTS (MPa) = 3.45 × HB, which is accurate for many low‑alloy and carbon steels with ±10% typical deviation. The interactive bar graph dynamically normalizes hardnesses to help visualize relative material hardness across scales.
Based on the data from ASTM E140‑12b standard for carbon steel/alloy steel, a common hardness conversion table has been generated, covering HRC, HB, HV, HRB (where applicable), and estimated tensile strength values for quick engineering reference. Conversion curves vary for different material categories (e.g., tool steel, cast iron). This table is applicable only to carbon steel/alloy steel.
| Rockwell C (HRC) | Brinell (HB) 10/3000 |
Vickers (HV) approx. |
Rockwell B (HRB) 1/16" ball |
Tensile Strength (UTS) MPa (approx.) |
|---|---|---|---|---|
| 20 | 218 | 229 | 95.1 | 752 |
| 25 | 252 | 265 | 102.0 | 869 |
| 30 | 285 | 299 | N/A | 983 |
| 35 | 325 | 341 | N/A | 1121 |
| 40 | 365 | 383 | N/A | 1259 |
| 45 | 415 | 436 | N/A | 1432 |
| 50 | 470 | 494 | N/A | 1622 |
| 55 | 530 | 557 | N/A | 1829 |
| 60 | 600 | 630 | N/A | 2070 |
| 65 | 670 | 704 | N/A | 2312 |
| 68 | 720 | 756 | N/A | 2484 |
This calculator implements ASTM E140-12b “Standard Hardness Conversion Tables for Metals” and ISO 18265:2021 “Metallic materials — Conversion of hardness values”. Material-specific adjustments are derived from SAE J417, ASM Metals Handbook, and AISI guidelines. The Exact Table Mode returns nearest reference values, eliminating interpolation uncertainty for audit compliance. Tolerance bands (±5%) visualize typical measurement scatter. PDF export captures full results for quality records.
A tier-1 automotive supplier needed to verify case‑hardened gears (spec: 58–62 HRC after carburizing). Using this converter, they quickly translated vendor-supplied Vickers (HV 670–750) into HRC equivalents (≈ 59–61 HRC), avoiding misinterpretation. The tensile strength estimator gave ≈ 1850 MPa, validating design safety margins. This prevented two batches of potential rejects and saved $34k in re‑certification costs.