There is a table below shows the comparisons of various surface roughness scales. The information contained in the table is based on the assumption that metal surfaces are being tested, kind of visual inspection and has subjectivity judgement , so the comparison values may vary by up to 25% and for reference only
Ra = Roughness Average in micrometers or microinches
RMS = Root Mean Square in microinches
CLA = Center Line Average in microinches
Rt = Roughness Total in microns
NN = NNew ISOISO ( d) (grade) scalel numbers b
Cut‐off Length = Length required for sample
