Free surface roughness calculator

Compares an Ra value with historical N classes and a user-selected Rz estimate.

Arithmetic mean roughness Ra

Assumed Rz/Ra ratio

How to use the result

Check the definition of the dimension and datum conditions on the drawing. The calculator does not replace inspection of the specific part.

Rz estimate = Ra · user-selected ratio

Sources: ISO 1302 legacy N-grade Ra values; current surface specification conventions must be checked separately.