3D Printer E-Step Calculator — extruder calibration

Calibrate extruder steps per millimetre from a measured extrusion, with the M92 command to paste.

Example: Commanding 100 mm extruded 108 mm — change E steps from 93 to 86.11.

Inputs

Current E steps/mm

From M503, or your firmware configuration.

Length commanded(mm)

Use G1 E100 F100 — slowly, so pressure does not distort the result.

Original mark distance(mm)

Where you marked the filament, measured from the extruder inlet.

Distance after extruding(mm)

Measure from the extruder to the mark again.

Result

New E steps/mm

86.111

Actually extruded: 108 mm
Extrusion error: +8%
Step change: -7.41%
Previous valuegiven: 93

The extruder moved 8 mm more than commanded, so it needs FEWER steps per mm — 93 down to 86.11.
Extrude slowly — G1 E100 F100 or less. At speed, pressure in the hotend and filament compression distort the measurement, and you end up calibrating out an effect that only exists at that speed.
Calibrate with the hotend at printing temperature and the nozzle clear. Cold extrusion loads the drive gear differently and will give a different, wrong answer.

; generated by urdb.io/tools/e-step-calculator
; 1. Heat the hotend to printing temperature
; 2. Mark the filament 120 mm from the extruder inlet
; 3. G1 E100 F100    ; extrude slowly
; 4. Measure from the extruder to the mark again

M92 E86.11   ; set the new value
M500              ; save to EEPROM

Formula

new steps = current steps × requested / actual

Worked example

Commanding 100 mm extruded 108 mm — change E steps from 93 to 86.11.

actual = mark distance − remaining distance
120 − 12
108 mm
new steps = current × requested / actual
93 × 100 / 108
86.111
Actual above requested means the ratio is below one, so steps go down.

Frequently asked questions

How do I calibrate extruder steps?

Heat the hotend, mark the filament a known distance from the extruder inlet, command a slow extrusion of 100 mm, then measure to the mark again. The difference is what actually went in, and new steps = old × requested / actual.

Under-extruding — do I raise or lower the steps?

Raise them. Steps per mm is how many pulses the firmware issues for each millimetre it wants; if the extruder moves too little, it needs more pulses per millimetre. Getting this backwards makes the problem worse and is the most common error in this procedure.

Why extrude slowly?

Because at speed, hotend pressure and filament compression add their own error. You would end up calibrating out an effect specific to that speed, and the result would be wrong at every other. F100 or slower keeps the measurement about the extruder alone.

My correction is over 20% — is that normal?

No. Real calibration is a few percent. A large correction usually means something mechanical: a slipping drive gear, the wrong gear ratio configured, or a partial jam. Fix that first — calibrating around it just hides the fault.

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