Hardness Conversion Calculator
Easily convert between different hardness scales such as Rockwell (HRC, HRB, HRA), Brinell (HB), Vickers (HV), and Knoop (HK).
Convert Hardness Value
Convert Hardness
Conversions between different hardness scales are often based on empirical formulas or conversion tables. This calculator makes estimated conversions between the most commonly used hardness scales.
Warning: These conversions are approximate and may not give completely accurate results, especially for very different hardness ranges or different material types. For precise applications, direct testing or reference to the material manufacturer's data is recommended.
Approximate Hardness Values for Common Materials
| Material | HRC | HRB | HB (Brinell) | HV (Vickers) |
|---|---|---|---|---|
| Mild Steel | - | ~60-90 | ~100-180 | ~100-180 |
| Medium Carbon Steel | ~10-25 | ~90-100 | ~180-250 | ~180-250 |
| Stainless Steel (Annealed) | - | ~70-95 | ~150-200 | ~150-200 |
| Hardened Steel | ~40-65 | - | ~370-600+ | ~370-800+ |
| Aluminum Alloys | - | ~30-80 | ~50-150 | ~50-150 |
| Rice | - | ~20-70 | ~50-150 | ~50-150 |
| Copper | - | ~20-50 | ~40-120 | ~40-120 |
This table provides a general reference only. The specific alloy of the material, the heat treatment state, and the testing conditions can significantly affect the hardness values.
What is Hardness and Why is it Important?
**Hardness** is a measure of a material's resistance to indentation, scratching, or abrasion. It is a fundamental mechanical property in engineering and materials science because it provides important information about a material's strength, wear resistance, and machinability. Hardness tests can be performed by non-destructive or semi-non-destructive methods and are often used to check material quality, evaluate heat treatment effects, and make material selection.
There are many different hardness measurement scales, each using different testing methods, indenter types, and applied loads. The most common are:
Common Hardness Scales:
-
Rockwell Hardness (HRC, HRB, HRA):
- **HRC (Rockwell C):** Used for very hard materials (hardened steels). Conical diamond tip indenter and high load (150 kg) are used.
- **HRB (Rockwell B):** Used for soft and medium hard metals (aluminum, brass, mild steel). 1/16 inch diameter steel ball and low load (100 kg) are used.
- **HRA (Rockwell A):** Used for very thin or very hard materials. Conical diamond tip indenter and lower load (60 kg) are used.
Rockwell tests give a direct hardness value and are quick to read.
-
Brinell Hardness (HB):
It is done using a large spherical hardened steel or carbide ball indenter with a higher load (e.g. 500, 1500, 3000 kg). It is generally preferred for softer and medium hard materials, such as cast iron with a large grain structure.
-
Vickers Hardness (HV):
It is done using a pyramid shaped diamond tipped indenter. It can be used in a wide range of both very soft and very hard materials. Loads can vary from very low to very high (e.g. 1 kgf - 120 kgf).
-
Knoop Hardness (HK):
It is made using very low loads with a small diamond pyramid indenter. It is particularly ideal for very thin materials, coatings or microhardness measurements.
Why is Hardness Conversion Necessary?
Different hardness testing methods have been developed for different application areas, material types and testing conditions. However, sometimes it is necessary to know the equivalent of a hardness value measured on one scale on another. These conversions allow direct comparisons, combining data from different sources and evaluating the suitability of testing equipment.
Hardness conversion formulas are usually empirically derived and therefore their accuracy may vary depending on the type of material, heat treatment, microstructure and hardness range. Conversions can show large deviations, especially for different material classes or hardness ranges. **In critical applications, direct test results or material manufacturer's conversion tables should always be used instead of values obtained from conversion.**