3D Printing Calculators

FDM calibration & firmware

Klipper Rotation Distance Calculator

Klipper does not use e-steps. It uses millimetres of filament per motor revolution. Calibrate with requested vs actual length, or convert an old M92 E value with the stepper geometry.

Inputs

Units
mm

Value already in printer.cfg. Typical BMG-class ~22.68 mm; un-geared ~33–40.

mm
mm

If actual is short, rotation_distance is too large — the calibrated value will drop.

200 for 1.8° motors, 400 for 0.9°.

steps/mm

M92 E. Used only for the from-e-steps conversion, but always calculated.

Driven/driving teeth, only if printer.cfg has the same gear_ratio (e.g. 50:17). Without a gear_ratio line, leave 1.

Results

rotation_distance to use
21.5441mm

Follows the mode dropdown.

From e-steps
34.4086mm
From measured lengths
21.5441mm

The Result is indicative and educational. It does not constitute a design, a technical opinion or medical advice and does not replace calculations or verification by a person with the appropriate qualifications and authorisations. Before purchase, installation or use in practice – in particular in electrical installations – the Result should be verified by a qualified specialist. Details: Terms of Service, point 4.

Example products

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Calculation method

Calibration: new rotation_distance = old × actual / requested. If the printer pushed only 95 mm when asked for 100 mm, rotation_distance was too high and must fall (the opposite of Marlin e-steps, which rise). From e-steps: rotation_distance = (full_steps_per_rev × microsteps × gear_ratio) / e_steps. Enter a gear ratio other than 1 only if printer.cfg has the matching gear_ratio line; without it, rotation_distance is per motor turn and the ratio must stay 1. Both numbers are always computed; the highlighted result follows the mode select. Lengths are millimetres. Invalid when any of requested, actual, e-steps, steps, microsteps or gear ratio is not positive.

Exact formula

new_rd = old_rd × actual / requested (too little extruded → smaller RD). from_esteps = (full_steps × microsteps × gear_ratio) / e_steps. Limits: A gear ratio other than 1 is only valid with the same gear_ratio line in printer.cfg; calibrate hot. The mode dropdown only picks which of the two always-computed results is primary.

Save it in printer.cfg

Under the extruder section: rotation_distance: the number this page gives. If you used a gear ratio other than 1, the same section needs gear_ratio (for example 50:17), or the extruder will be off by that ratio. Then reprint the 100 mm test.

Frequently asked questions

Why is this the inverse of e-steps?

E-steps are pulses per millimetre. Rotation_distance is millimetres per revolution. More pulses/mm means fewer millimetres per turn.

Do I still set pressure advance after this?

Yes. Rotation_distance is the hardware millimetres. PA and slicer flow are separate.

What gear ratio for a BMG clone?

Many are 50:17 ≈ 2.94, but clones wander. Enter it here only if printer.cfg also has gear_ratio: 50:17. Convert from e-steps only as a first guess, then run the 100 mm test.

Should I disconnect the hotend?

Follow your firmware guide. Measuring with melt pressure in the way under-reports actual length.

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