Stepper Motor Steps/mm Calculator

Stepper motors move in discrete steps. The number of steps per millimeter of travel sets the theoretical positioning resolution and must be configured correctly in firmware before any other calibration makes sense.

Belt-driven axes (X, Y)

steps_mm = (motor_steps x microstepping) / (belt_pitch x pulley_teeth)

A standard NEMA 17 motor has 200 full steps per revolution. With 16x microstepping, that is 3200 microsteps per revolution. A GT2 belt has a 2mm pitch; a 20-tooth pulley moves 40mm per full revolution. So: 3200 / 40 = 80 steps/mm. This is the most common value for belt printers.

Changing pulley size changes steps/mm. A 16-tooth pulley gives 100 steps/mm. A 24-tooth pulley gives 66.7 steps/mm. Larger pulleys increase speed at a given step rate but reduce theoretical resolution.

Leadscrew axes (Z)

steps_mm = (motor_steps x microstepping) / lead_mm

Lead is the distance the nut travels per full screw revolution. It is not the same as pitch on multi-start screws. A T8 leadscrew with 4-start threads and 2mm pitch has 8mm lead. An M5 leadscrew typically has 0.8mm pitch and 0.8mm lead.

Example: 200 steps, 16x microstepping, 8mm lead: 3200 / 8 = 400 steps/mm.

Extruder

steps_mm = (motor_steps x microstepping x gear_ratio) / (pi x hobb_diameter)

A BMG extruder with 3:1 gear ratio and 7.5mm hobbed gear: 3200 x 3 / (pi x 7.5) = 9600 / 23.56 = 407.4 steps/mm.

Fill in only the fields relevant to your axis type. The calculator uses the axis type selector to pick the correct formula.