Extruder Calibration: E-steps and Rotation Distance

Logan F.

Does Your Printer Extrude What It Thinks It Does?

Every G-code command that moves your extruder specifies the filament in millimetres: "Extrude 50 mm of filament." The printer converts this millimetre value into stepper motor steps using a conversion factor called e-steps (in Marlin) or rotation_distance (in Klipper). If this factor is incorrect, even by a few percent, the printer systematically over- or under- extrudes on every single move for every single print. Flow rate calibration (see our flow rate guide) can compensate for some of this error, but true e-step calibration is the cleaner, more fundamental fix. Do this first.

The 100mm Extrusion Test

The calibration procedure is elegantly simple. Mark the filament at 120mm from the extruder entry point using tape and a felt tip pen. In your printer's terminal (USB or network connection), send G92 E0 (reset extruder position to zero), then G1 E100 F100 (extrude 100 mm at 100 mm/min, slow enough for accuracy). Wait for the move to complete. Measure how much filament actually passed through the extruder entry point. If you marked at 120 mm and the mark is now at 27 mm, exactly 93 mm has moved, 7 mm short of the commanded 100 mm. You're under extruding by 7%.

Calculate the corrected value: Current e-steps × (commanded distance / actual distance) = new e-steps. If your current e-steps are 93 and you extruded 93 mm when commanding 100 mm: 93 × (100/93) = 100.0 e-steps. Apply with M92 E[value] in Marlin (and save with M500) or update rotation_distance in Klipper's printer.cfg (rotation_distance = old_value × (actual_distance / commanded_distance)). Retest: the answer should now be 100 mm ± 0.5 mm.

Why E-steps Drift and When to Recalibrate

E-steps are a mechanical constant of the extruder, gear ratio, stepper tooth count, and driver microstepping. They shouldn't drift unless you change hardware. You should recalibrate for these reasons: replacing the extruder gears or motor, switching extruder models (e.g., from a stock extruder to a Bondtech or Orbiter), or noticing systematic over/under extrusion that flow rate calibration alone can't explain. E-steps don't drift with temperature or filament type; those variations are handled by flow rate calibration. Verify e-steps once per major hardware change, then focus on per filament flow rate and pressure advance calibration for ongoing quality optimisation.

Extruder Calibration vs Flow Rate Calibration

These two calibrations are complementary but distinct. E-steps/rotation_distance calibrates the mechanical accuracy of the extruder; it should extrude exactly the commanded volume. Flow rate calibration (extrusion multiplier) adjusts for filament specific factors that affect how much plastic actually ends up in the print: diameter variation, melt characteristics, and gear slip. Do e-steps first (once per hardware change), then flow rate calibration per filament. A well calibrated extruder with per-filament flow rates produces the most dimensionally accurate prints possible on your setup. Combine with quality, consistent filament from OzFDM for the best dimensional repeatability.