Wood Lathe Speed Calculator
Calculate optimal lathe RPM for your workpiece diameter.
Get safe and efficient lathe speeds for turning wood bowls, spindles, and blanks.
Recommended RPM
Lathe speed should be chosen to give a peripheral (surface) speed of 400–600 metres per minute for most woodturning operations. Larger workpieces must spin slower to keep the rim speed within this safe range.
Speed formula: RPM = (surface speed × 1000) / (pi × diameter) Simplified: RPM ≈ 6,000 / diameter (mm) — gives the midpoint of the safe range
Surface speed guide:
- Roughing large bowls (100+ mm): 300–400 m/min → lower RPM
- General turning (50–100 mm): 500–700 m/min → medium RPM
- Spindle turning, small pieces (<50 mm): 700–1000 m/min → higher RPM
- Finishing / sanding: reduce 20–30% from turning speed
Common speed ranges by workpiece:
| Workpiece Diameter | Recommended RPM |
|---|---|
| 300 mm (12 in) bowl | 300–500 RPM |
| 200 mm (8 in) bowl | 500–750 RPM |
| 150 mm (6 in) bowl | 700–1,000 RPM |
| 100 mm (4 in) bowl | 1,000–1,500 RPM |
| 50 mm spindle | 2,000–2,500 RPM |
| 25 mm spindle | 3,000–4,000 RPM |
Safety rules:
- Always start the lathe at low speed and increase gradually
- Out-of-round or unbalanced blanks must be roughed at low speed
- Never exceed the lathe’s maximum rated RPM
- Always wear a face shield — not just safety glasses
- Stand to the side when starting, not directly in front of the work