Rockwell Hardness Conversion Calculator
Convert between different Rockwell hardness scales
How to Use This Calculator
Enter Hardness Value
Input the Rockwell hardness value you want to convert. This is typically a number from your hardness testing equipment or material specification.
Select Source Scale
Choose the Rockwell scale (HRA, HRB, HRC, etc.) that corresponds to your input value. Different scales use different indenters and loads.
Select Target Scale
Choose the Rockwell scale you want to convert to. Common conversions include HRC to HRB or HRA to HRC.
View Converted Value
Click "Convert" to see the equivalent hardness value in the target scale. Note that conversions are approximate and may have some uncertainty.
Rockwell Hardness Scales
| Scale | Indenter | Load (kgf) | Typical Use |
|---|---|---|---|
| HRA | Diamond cone | 60 | Very hard materials, thin materials |
| HRB | 1/16" steel ball | 100 | Soft metals, brass, annealed steel |
| HRC | Diamond cone | 150 | Hardened steel, hard metals |
| HRD | Diamond cone | 100 | Thin materials, medium-hard materials |
| HRE | 1/8" steel ball | 100 | Softer materials, cast iron |
| HRF | 1/16" steel ball | 60 | Thin soft materials |
| HRG | 1/16" steel ball | 150 | Soft to medium materials |
| HRH | 1/8" steel ball | 60 | Soft materials, aluminum |
| HRK | 1/8" steel ball | 150 | Soft to medium materials |
About Rockwell Hardness Conversion Calculator
The Rockwell Hardness Conversion Calculator is an essential tool for converting hardness values between different Rockwell scales. Rockwell hardness testing is one of the most common methods for measuring material hardness, but different scales (HRC, HRB, HRA, etc.) are used for different materials and applications.
When to Use This Calculator
- Material Specification: Convert hardness values between different specification standards
- Quality Control: Compare hardness measurements from different testing scales
- Material Selection: Understand equivalent hardness values across different scales
- Manufacturing: Interpret hardness requirements in different scale formats
- Research & Development: Analyze hardness data from various testing methods
Why Use Our Calculator?
- ✅ Multiple Scales: Convert between 9 different Rockwell scales
- ✅ Quick Conversion: Instant conversion results
- ✅ Accurate Approximations: Uses established conversion relationships
- ✅ Convenient Tool: No need for lookup tables or manual calculations
- ✅ Educational Resource: Learn about different Rockwell scales and their applications
Understanding Rockwell Hardness
Rockwell hardness testing measures the depth of penetration of an indenter under load. Different scales use different indenters (diamond cone or steel ball) and loads (60, 100, or 150 kgf). The hardness number is inversely related to the depth of penetration - harder materials have higher numbers.
Important Notes
- Conversions are approximate and may have uncertainties of ±2-5 HR units
- Exact conversions depend on material type and composition
- For critical applications, direct measurement in the desired scale is recommended
- HRC is the most commonly used scale for hardened steels
- HRB is commonly used for softer materials like brass and annealed steels
Frequently Asked Questions
What is the most common Rockwell scale?
HRC (Rockwell C) is the most commonly used scale, especially for hardened steels. It uses a diamond cone indenter with a 150 kgf load and is ideal for materials with hardness between 20-70 HRC.
Why are there so many Rockwell scales?
Different scales use different indenters and loads to accurately measure hardness across a wide range of materials. Soft materials require ball indenters, while hard materials use diamond cones. Different loads accommodate different material thicknesses and hardness ranges.
How accurate are Rockwell hardness conversions?
Conversions are approximate with typical uncertainties of ±2-5 HR units. Accuracy depends on material type, as conversion relationships vary between different alloys and heat treatments. For critical applications, direct measurement is recommended.
Can I convert Rockwell to other hardness scales like Vickers or Brinell?
Yes, but this calculator only handles Rockwell-to-Rockwell conversions. For conversions to Vickers (HV), Brinell (HB), or other scales, you would need specialized conversion calculators or tables.
What's the difference between HRC and HRB?
HRC uses a diamond cone indenter with 150 kgf load for hard materials (typically 20-70 HRC). HRB uses a 1/16" steel ball with 100 kgf load for softer materials (typically 60-100 HRB). HRC is for hardened steel, while HRB is for annealed steel, brass, and softer alloys.