Stepper Steps Per mm Calculator
A belt-driven 3D printer or CNC axis converts motor rotation into linear travel through a toothed pulley and belt. The firmware must know how many microsteps equal one millimeter of motion. That value is the microsteps per revolution divided by the linear travel per revolution. Microsteps per revolution is the motor's full steps multiplied by the microstepping factor; travel per revolution is the pulley tooth count multiplied by the belt pitch. This calculator computes the steps-per-mm value you enter with the M92 firmware command, along with the travel per revolution for reference.
Steps per mm formula
Microsteps per rev = full steps * microstepping
Travel per rev (mm) = pulley teeth * belt pitch
Steps per mm = microsteps per rev / travel per rev
Resolution per microstep = travel per rev / microsteps per rev
This is the belt-and-pulley form. For a 200-step motor, 16x microstepping, a 20-tooth pulley, and 2 mm GT2 belt, steps per mm equals 3,200 divided by 40, which is 80.
Steps per mm context
- 1.8 degree motors give 200 full steps per revolution; 0.9 degree motors give 400.
- GT2 belt has a 2 mm tooth pitch, the consumer standard.
- 16x microstepping is a common default; the firmware commands microsteps.
- Set the value with M92 and persist it with M500 in Marlin firmware.
- Calibrate by commanding a known move, measuring travel, and scaling proportionally.
Steps per mm: frequently asked questions
How do I calculate steps per mm for a belt-driven axis?
Multiply the motor's full steps per revolution by the microstepping factor to get microsteps per revolution. Divide that by the distance the belt travels in one revolution, which is the pulley tooth count times the belt pitch in millimeters. The result is microsteps per millimeter, the value you set in firmware with M92.
What is the motor step angle and steps per revolution?
Most 3D printer steppers have a 1.8 degree step angle, which is 200 full steps per revolution (360 divided by 1.8). Some are 0.9 degree, or 400 steps per revolution. Enter the value for your motor.
What belt pitch should I use?
GT2 belt has a 2 mm tooth pitch, the most common on consumer printers. A 20-tooth GT2 pulley therefore moves 40 mm per motor revolution. Enter your belt's pitch and your pulley's tooth count.
Why does microstepping appear in the formula?
Stepper drivers subdivide each full step into microsteps, commonly 16. The firmware commands microsteps, so the steps per mm value must include the microstepping factor to convert commanded microsteps into real travel.
How do I apply the result?
Set it in your firmware with the M92 command, for example M92 X80 for 80 steps per mm on the X axis, then save with M500. Calibrate by commanding a known move and measuring the actual distance, adjusting proportionally.
Official sources
- Marlin firmware documentation: M92 Set Axis Steps-per-unit.
- RepRap project documentation: Calibration guide.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.