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Converter — enter any value

Ra Arithmetic mean roughness μm — Range: 0.012 – 50
Rz Mean roughness depth μm — Rz ≈ 4 × Ra (approx.)
N Roughness grade (ISO 1302) N1 (finest) to N12 (roughest)
Arithmetic mean
Ra μm
Mean depth
Rz μm
ISO grade
N-grade

N-grade reference (ISO 1302)

N Ra (μm) Rz (μm) Surface quality Typical processes

Achievable Ra by manufacturing process

Full range   Typical range

Surface finish symbols (ISO 1302)