Slicer Setting

Extrusion Multiplier & Flow Rate

Updated August 2026
3D Printing Definition
Definition

Extrusion multiplier (also known as flow rate in firmware) is a scaling factor (typically expressed as 0.90 to 1.10, or 90% to 110%) that multiplies the calculated G-code extrusion volume to fine-tune the exact amount of molten plastic pushed by the extruder gears.

Diagnosing Over-Extrusion vs Under-Extrusion

If the flow rate is too high (over-extrusion), parts develop rough top surfaces, nozzle dragging scars, and dimensional bloat. If too low (under-extrusion), gaps appear between perimeter wall lines, resulting in brittle, fragile parts.

Wall Thickness & Caliper Tuning Method

To calibrate flow rate precisely, operators print a single-wall hollow cube in vase mode and measure the wall thickness with digital calipers, adjusting the slicer flow percentage until the measured wall matches the slicer line width setting exactly.

Filament Density & Spool Variance

Different filament brands and colors exhibit slight variances in polymer density and nominal diameter (1.75 mm ±0.03 mm). Calibrating the flow rate per material preset ensures repeatable print accuracy across production batches.

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