Surface quality / Unit calculator
Convert roughness units. Keep the parameter.
Ra alone does not determine Rz. Measure or obtain the required parameter using the specified standard and conditions.
Looking for a Ra-to-Rz conversion? See why a fixed multiplier cannot give an equivalent value →
Your converted value
Enter a value and select its unit. Ra stays Ra; Rz stays Rz.
Formula and worked example
1 µin = 0.0254 µm exactly. Divide a µm value by 0.0254 to get µin; multiply a µin value by 0.0254 to get µm.
Ra 1.6 µm ÷ 0.0254 ≈ Ra 62.992126 µin. This is the same parameter expressed in another unit.
Unit basis: NIST international inch definition ↗. The displayed result uses up to 9 significant digits. The rounding is computational, not an uncertainty or instrument-resolution statement.
This calculation does not choose a filter, evaluation length, manufacturing process or acceptance limit. Numerical zero is accepted for arithmetic; it is not a claim about an attainable finish.