3D Print Speed & Volumetric Flow
Top print speed from a hotend’s volumetric flow at your layer height and line width, the flow a speed needs, filament feed rate and a floor on print time.
The top print speed a hotend’s maximum flow allows at your bead size, or the flow a chosen speed demands, the filament feed rate, and the least time the part’s material takes to extrude.
Example: A hotend rated at 15 mm³/s prints a 0.2 × 0.45 mm line at 166.7 mm/s at most; a 40 cm³ part then needs at least 44 minutes of extrusion.
Speed times
the bead.
What volumetric flow is, how it caps print speed, what the filament feed rate means, and why the time here is a floor.
Flow
A printer lays a bead as tall as the layer and as wide as the line, so every second at speed v it melts v × h × w cubic millimetres of plastic. A hotend can melt only so much — its maximum volumetric flow, from the maker or your own test — so the top speed at a bead size is that flow over h × w.
Filament and time
The filament enters at the flow divided by its cross-section, π·d²/4 — the rate the extruder must push. A part’s material volume from the slicer divided by the flow is the time spent extruding at full speed: a lower bound, because travel moves, acceleration, small layers and cooling pauses all add to it.
What the number does not settle
Acceleration and cooling usually limit speed before the hotend does, and the slicer’s time estimate is the one to plan by. Inputs stay in your browser; the same anonymous usage counts as the rest of the site apply.