A Rockwell hardness measurement is reported as a Rockwell hardness number, without units. The Rockwell hardness number is calculated from the difference in the indentation depths before and after application of the total force, while maintaining the preliminary test force. The difference in indentation depths is measured as h as described above. The calculation of the Rockwell hardness number is dependent on the specific combination of indenter type and the forces that are used.
For scales that use a ball indenter, the Rockwell hardness number is calculated from h (in mm) as:
Regular Rockwell Hardness=-130 0 002 h/mm
Rockwell Superficial Hardness=-100 0 001 h/mm