E-Steps Calculator (Marlin & Klipper Rotation Distance)

The test, step by step

1. Heat the hotend to your normal printing temperature so filament can actually flow. Leave the nozzle over empty air or above the bed.
2. Using calipers, mark the filament 120 mm above the point it enters the extruder (the top of the extruder body, or the end of the Bowden coupler). A second mark at 110 mm helps if the first gets pulled inside.
3. Set relative extrusion and push 100 mm slowly: M83 then G1 E100 F100. The slow feed rate (100 mm/min) keeps the hotend from fighting the extruder — fast extrusion tests under-read because the melt can't keep up.
4. Measure from the extruder entry to the mark. Ideally 20 mm remains. If more remains, the extruder pushed less than asked (under-extrusion); if less, it pushed more.
5. Enter your current value and the measurements above, save the new value with the commands shown, and run the test again. A second pass within ±0.5 mm is as good as it gets.

The formulas

They're inverses because the two firmwares describe the extruder in opposite units. Marlin counts steps per millimeter of filament, so under-extrusion means more steps are needed. Klipper describes millimeters per motor revolution, so under-extrusion means each revolution moved less than the config assumed, and the number comes down. Mixing them up moves you twice as far from correct — the calculator won't let you.

When the number is far off

A genuine e-steps error is small — a few percent from manufacturing tolerance in the drive gear, or from an upgrade like a dual-gear extruder or a different motor. A result more than 10% away from what you had usually means something else is going on:

• Slipping or grinding. The drive gear is skating on the filament: idler tension too low, a partial clog, or the hotend too cold for the speed. Look for a shiny worn spot on the filament.
• Extruding too fast. 100 mm at F100 is right; at F300 many hotends can't melt fast enough and the reading is meaningless.
• Measuring from the wrong place. On a Bowden printer measure from the extruder, not the hotend.
• Absolute extrusion mode. Without M83, G1 E100 means "go to E=100", which may be 0 mm or 100 mm depending on the current E position. Send M83 first, or G92 E0 then the move.
• A stepper motor with a different step angle (0.9° instead of 1.8°) or a geared extruder swap. These legitimately double or triple the value — the warning still fires, and that's fine if you know why.

What e-steps don't fix

E-steps make the extruder deliver the right length of filament. They don't correct for filament diameter variation, for how the plastic spreads at a given temperature, or for the slicer's assumptions about line width. That's the job of the flow rate, tuned per material after e-steps are set. Do this first, once per extruder; then use the flow rate calculator for each filament; then check dimensions with the shrinkage calculator. Doing them in another order means re-doing them.

Note that the popular Bambu Lab, Prusa MK4 and most Klipper-based printers ship with the extruder already calibrated and tuning flow is all that's normally needed. E-steps matter most on printers that have been modified — a new extruder, a new motor, a new mainboard — or on budget machines where the stock number was never right.