Volumetric flow and max speed calculator

How it is calculated

flow (mm³/s)   = layer height × line width × speed
max speed      = max flow ÷ (layer height × line width)

This treats the extruded line as a rectangle. Slicers use a slightly rounded cross-section, so their figure is a few percent lower. For checking a speed limit the rectangle is the safe side.

Why this matters more than the speed on the box

A printer can move at 500 mm/s and still be unable to print at 500 mm/s. Doubling layer height doubles the plastic needed per second. A 0.6 mm nozzle at 0.3 mm layers needs over twice the flow of a 0.4 mm nozzle at 0.2 mm, at the same speed. When demand passes what the hotend can melt, you get under-extrusion: thin walls, gaps and weak layers.

Finding your own max flow

The limit depends on the hotend, the nozzle, the temperature and the filament, so a single published number is a rough guide at best. Few manufacturers state one. Orca Slicer has a built-in max volumetric speed test (Calibration menu) that prints a part at rising flow; the point where the surface turns matte or gappy is your limit. Set the slicer's max volumetric speed a little below it, per filament, and the slicer will cap speeds for you.

Related: e-steps calculator · filament temperature chart.