Calculator guide
GT2 Pulley Steps per mm: 16T vs 20T Explained
How tooth count changes travel per revolution and the steps/mm value in your firmware.
On a belt-driven axis, each motor revolution moves the belt by teeth x pitch. For GT2 the pitch is 2 mm, so a 20-tooth pulley moves 40 mm per revolution.
The formula
steps/mm = (motor full steps per rev x microsteps) / (pulley teeth x 2 mm)
| Pulley | Travel per rev | steps/mm (1.8° motor, 1/16 microstep) |
|---|---|---|
| GT2 16T | 32 mm | 100 |
| GT2 20T | 40 mm | 80 |
| GT2 30T | 60 mm | 53.33 |
| GT2 40T | 80 mm | 40 |
A 1.8° motor has 200 full steps per revolution; a 0.9° motor has 400, which doubles the values above.
16T or 20T?
- 16T: more steps per mm and a bit more force at the belt; the belt wraps a smaller diameter.
- 20T: the most common choice on 3D printers; faster travel per revolution and gentler belt bending.
Whatever you choose, match the pulley width to the belt (6 mm belt on a 6 mm pulley) and the bore to the motor shaft (usually 5 mm on NEMA 17).
Shop: GT2 pulleys · GT2 belts
See also: choosing a pulley · pulley bore size · belt length calculation
Need a size that is not listed?
Tell us the bore sizes, model and quantity. No minimum order, formal quotes in USD, worldwide shipping.
Request a quote