Wood Lathe Speed Calculator (Safe RPM by Diameter)

How fast should the lathe spin? The usual woodturning rule is that the diameter in inches times the RPM should stay between 6,000 and 9,000: start near the low end and never go over the high end. Enter the diameter of the blank, in inches or millimetres, and this calculator gives the starting speed, the range for a round and balanced piece, the absolute maximum, and the rim speed it works out to. It also tells you if your lathe’s lowest speed is too fast for the blank.

Wood lathe speed calculator

How it works

Starting speed = 6,000 ÷ diameter in inches
Maximum speed = 9,000 ÷ diameter in inches
Rim speed = π x diameter x RPM ÷ 12 (feet per minute)

Holding diameter x RPM constant is the same as holding the rim speed constant: at 9,000 the outside of any blank moves at about 2,360 ft/min (12 m/s), whatever its size. That is why a 12 in bowl blank is turned at a few hundred RPM and a 2 in spindle can run at thousands.

Worked example

A 10 in bowl blank, already trued up:

Units: Inches
Diameter of the blank: 10 in
Blank: Round and balanced
Your lathe’s lowest speed (optional): 0 rpm

The calculator gives:

Start at: 600 rpm
Speed range once round and balanced: 600 to 900 rpm
Never exceed: 900 rpm (9,000 / 10 in)
Rim speed at the maximum: 2,356 ft/min (12 m/s)

Start at 600 RPM (6,000 ÷ 10) and do not go past 900 RPM (9,000 ÷ 10). If the same blank were still a rough, out-of-balance chunk with bark on it, you would start below 600 RPM and speed up only as the vibration settles. On a lathe whose slowest speed is 1,000 RPM, this blank is too large to turn safely.

Wood lathe speed chart

Diameter	Start (6,000 ÷ D)	Maximum (9,000 ÷ D)
2 in (51 mm)	3,000 rpm	4,500 rpm
3 in (76 mm)	2,000 rpm	3,000 rpm
4 in (102 mm)	1,500 rpm	2,250 rpm
6 in (152 mm)	1,000 rpm	1,500 rpm
8 in (203 mm)	750 rpm	1,130 rpm
10 in (254 mm)	600 rpm	900 rpm
12 in (305 mm)	500 rpm	750 rpm
14 in (356 mm)	430 rpm	640 rpm
16 in (406 mm)	380 rpm	560 rpm
18 in (457 mm)	330 rpm	500 rpm
20 in (508 mm)	300 rpm	450 rpm
24 in (610 mm)	250 rpm	380 rpm

Speeds rounded to the nearest 10 RPM. For blanks out of balance or with defects, start lower.

Notes and limits

The rule assumes sound, balanced wood. Cracks, bark inclusions, voids and heavy off-centre blanks call for lower speeds, and a face shield is worth wearing at any speed.
Always start the lathe at its lowest speed setting and bring it up. Check the speed is back at the bottom before you switch on with a new blank.
Stand out of the line of rotation when you switch on a new or unbalanced blank.
If the lathe vibrates or walks, slow down. The figure here is a ceiling, not a target.
Very small diameters give numbers above what most lathes can do, and above what most turners use for spindles. The lathe’s maximum still applies.

Frequently asked questions

What speed should I turn a 10 inch bowl?

Start at about 600 RPM and stay under 900 RPM once it is round and balanced (6,000 ÷ 10 and 9,000 ÷ 10).

What is the formula for wood lathe speed?

Diameter in inches x RPM should be between 6,000 and 9,000. Divide 6,000 by the diameter for a starting speed and 9,000 by the diameter for the maximum.

How fast should a wood lathe spin for spindles?

For a 2 in spindle the rule gives 3,000 to 4,500 RPM, which is faster than many lathes go. Treat it as a ceiling: start slower and speed up only while the cut stays smooth and controlled.

Why turn big bowls slower?

Because the outside of a large blank moves much faster at the same RPM. A 16 in blank at 1,000 RPM has a rim speed of over 4,000 ft/min, almost twice the 9,000-rule limit.

Can I use millimetres?

Yes. Switch the units to millimetres. The calculator converts to inches for the rule (diameter in mm ÷ 25.4).

Sources

Turn a Wood Bowl, "Safe Wood Lathe Speed": diameter in inches x RPM kept between 6,000 and 9,000; maximum RPM = 9,000 / diameter

Last reviewed: 16 October 2026. The calculation is covered by automated tests with known answers taken from the sources above. Found an error? Please let us know.