Below is a comprehensive graphic for surface finishes that we hope you find useful. The Surface Roughness Conversion Chart will help to convert surface finish between selected industry standard units. The Common Names table lists some common surface finish names and how they are defined by their Ra number. Lastly, the Sanitary & BPE Surface Finishes table defines the surface finish requirements as established by the ASME BPE 2016 Standard. This table is also useful in that it relates surface finish codes from various manufacturers to the ASME BPE Standard.
N = New ISO (Grade) Scale numbers
Ra = Roughness (average), measured in microinches (µin) or micrometers (µm)
RMS = Root Mean square, microinches (µin)