What is an extrusion multiplier?

It is a scaling factor your slicer applies to every extrusion move. A value of 1.0 means the slicer trusts the printer to extrude exactly the length requested; any other value compensates for consistent over- or under-extrusion.

How do I measure test prints for flow calibration?

Print a hollow cube with zero infill and 1 or 2 perimeters. Measure the wall thickness around mid-height on each side using calipers, avoiding the base squish, and calculate the average.

Is this the same as flow rate percentage in Cura or PrusaSlicer?

Yes. Slicers like PrusaSlicer, Bambu Studio, and OrcaSlicer use a decimal multiplier (1.00 = 100%), while Cura and others use flow percentages (100%). A result of 0.95 equals 95% flow.

What if my result is far from 1.0?

A result outside roughly 0.85 to 1.15 often indicates a mechanical issue (slipping extruder gear, partially clogged nozzle, or loose belt) or incorrect filament diameter in slicer settings.

Should I recalibrate for every filament?

Yes, ideal extrusion multiplier varies by material type, brand, and color due to differences in filament diameter tolerance, density, and die swell.

Does this replace E-steps calibration?

No. E-steps (rotational distance) calibrates mechanical extruder gear movement using a 100mm filament feed test in firmware. Extrusion multiplier is a slicer-level setting calibrated per filament spool to account for material viscosity and line width.

Extrusion Multiplier Calculator

Enter your target line width or requested feed, measured dimension, and current multiplier to get the corrected flow rate for your slicer.

Calibration Inputs

Expected line width or feed length (mm)

Actual measured width or length (mm)

Current multiplier / flow rate

Enter your measurements to get the corrected multiplier

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Summary

Extrusion multiplier (flow rate) calibration fine-tunes slicer output to match real printed line dimensions or extruder feed distance. Calibrate with a hollow single- or double-wall test print measured with calipers, or a measured filament feed test. Enter your expected dimension, measured actual dimension, and current multiplier to get the exact value for PrusaSlicer, Bambu Studio, OrcaSlicer, or Cura.

How it works

Slice and print a hollow calibration cube (0% infill, 0 top layers) with a known wall perimeter thickness.
Measure the actual wall thickness at several points using calipers or a micrometer, and take the average.
Alternatively, mark 100mm of filament above your extruder gear and measure the actual feed distance.
Enter your expected target dimension, actual measured dimension, and current multiplier below.
The calculator applies: New Multiplier = Current Multiplier × (Expected / Measured).
Enter the corrected multiplier into your slicer's flow rate or extrusion multiplier setting.

Use cases

Calibrate a new hotend or extruder after a hardware swap.
Fix visible over-extrusion (blobbing, oozing) or under-extrusion (gaps, weak layers).
Recalibrate after switching filament brands or materials with different diameters.
Dial in flow rate for a new nozzle size.
Verify extrusion accuracy as part of routine printer maintenance.
Cross-check a slicer flow percentage against a firmware E-steps value.

Frequently Asked Questions

Last updated: 2026-09-09 · Reviewed by Nham Vu