What is the E-steps formula?

New E-steps = current E-steps x (requested length / actual extruded length). If you asked for 100mm and only 95mm came out, the extruder under-extrudes, so the new value rises by the ratio 100/95 to compensate.

How do I measure the actual extruded length?

Mark the filament at a known distance from the extruder entry (e.g. 120mm). Command 100mm of extrusion. Then measure from the entry to the mark again. Actual extruded = start distance minus remaining distance. If 30mm remains from a 120mm start, 90mm was extruded.

Why mark 120mm but extrude only 100mm?

Marking further than you extrude keeps the mark above the extruder, so it stays measurable and never disappears into the hotend. The 20mm buffer is just a safety margin; only the requested-vs-actual ratio matters for the math.

How do I save the new value?

On Marlin send M92 E to set it, then M500 to write it to EEPROM so it survives reboots. On Klipper, E-steps are expressed as rotation_distance; scale it by actual/requested (the inverse ratio) in your config and restart.

Should I calibrate E-steps or flow rate first?

Always E-steps first. E-steps make the extruder physically push the correct length of filament. Flow rate is a software multiplier layered on top for fine volumetric tuning. Calibrating flow before E-steps just masks a mechanical error.

E-Steps Calibration Calculator

This calculator gives you the corrected extruder steps-per-mm (E-steps) value from a single calibration measurement. Accurate E-steps are the foundation of good prints — without them, every flow, dimensional, and strength setting is built on a wrong baseline.

How it works

E-steps tell the firmware how many motor steps equal one millimetre of filament fed. When you command 100mm of extrusion and measure a different amount, the ratio tells you how to correct the value:

New E-steps = current E-steps x (requested length / actual extruded)

Under-extrusion (less came out than requested) makes the ratio greater than 1, so E-steps rise. Over-extrusion makes the ratio less than 1, so E-steps fall.

The procedure

Read current E-steps with M503 (look for the M92 line) or M92 alone.
Mark the filament a known distance above the extruder entry — say 120mm.
Heat the hotend and command G1 E100 F100 to extrude 100mm slowly.
Measure from the entry point to your mark. Subtract from the start distance: actual = 120 - remaining.
Enter current E-steps, requested 100mm, and the actual figure below.
Save with M92 E<new> then M500.

Worked example

Current E-steps: 93.0
Requested: 100mm
Actual extruded: 96mm (24mm remained from a 120mm mark)

New E-steps = 93.0 x (100 / 96) = 96.875. Round to 96.88 and save. The extruder was under-extruding by 4%, so the value rose by exactly that ratio.

Notes

Extrude slowly (F100, i.e. 100 mm/min) so the motor never skips and the measurement is clean.
For Klipper, convert to rotation distance: new_rotation = current_rotation x (actual / requested) — note the inverse ratio versus Marlin E-steps.
Re-verify after the first correction; a second pass should land within a fraction of a percent.

All math runs locally in your browser.