Ra Rz Conversion Chart
Reference chart for common Ra and estimated Rz surface roughness values.
Use this Ra Rz conversion chart as a quick engineering reference for common surface roughness values.
Common Ra to Rz Chart
| Ra (µm) | Est. Rz (µm) | Typ. min (µm) | Typ. max (µm) |
|---|---|---|---|
| 0.1 | 0.5 | 0.4 | 0.7 |
| 0.2 | 1 | 0.8 | 1.4 |
| 0.4 | 2 | 1.6 | 2.8 |
| 0.8 | 4 | 3.2 | 5.6 |
| 1.6 | 8 | 6.4 | 11.2 |
| 3.2 | 16 | 12.8 | 22.4 |
| 6.3 | 31.5 | 25.2 | 44.1 |
| 12.5 | 62.5 | 50 | 87.5 |
| 25 | 125 | 100 | 175 |
| 50 | 250 | 200 | 350 |
Est. Rz = Ra × 5 · Typical range = Ra × 4 to Ra × 7 (µm)
How to Read This Chart
The estimated Rz column uses the common ratio Rz ≈ Ra × 5. The typical range column uses Rz ≈ Ra × 4 to 7.
Ra and Rz cannot be converted exactly. This calculator provides estimated engineering reference values only. Actual results may vary depending on surface profile, material, machining process, cutoff length, and measurement method.
FAQ
Can Ra be converted directly to Rz?▼
No. Ra and Rz describe different surface roughness characteristics. This calculator provides an estimated value only.
What is the common Ra to Rz formula?▼
A common engineering estimate is Rz ≈ Ra × 5. A broader reference range is Rz ≈ Ra × 4 to 7.
Is Rz always 5 times Ra?▼
No. The ratio depends on surface profile, machining process, material, cutoff length, and measurement method.
How do I convert Rz to Ra?▼
Use the Rz→Ra calculator or bidirectional mode. A common engineering estimate is Ra ≈ Rz ÷ 5, with a broader reference range of Ra ≈ Rz ÷ 7 to Rz ÷ 4. Results are approximate only.