Calculate nozzle flow

Estimate the print speed allowed by nozzle geometry and hotend volumetric flow.

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ToolNozzle Flow Calculator
Input
Output
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Preview

How it works

Line width is nozzle diameter times a width multiplier, and bead cross-section is line width times layer height. Maximum speed is volumetric flow divided by that area.

  • A 1.2 multiplier represents a common wider bead.
  • Flow rating depends on hotend, material, and temperature.

Worked example

A stock 0.4mm hotend
Rated for about 11mm3/s, a common figure for an unmodified PTFE-lined hotend
Input
											Nozzle diameter mm: 0.4
Layer height mm: 0.2
Max volumetric flow mm3 s: 11
Output
												Line width mm: 0.48
Cross section mm2: 0.096
Max speed mm s: 114.6
Max speed mm min: 6875

When to use this

High-flow slicer limits, hotend tests, and large-nozzle setup checks use this estimate.

Edge cases

  • Doubling layer height halves speed at the same flow.
  • A PLA flow test does not transfer unchanged to abrasive or high-temperature filament.
  • Acceleration, cooling, and motion limits are not modeled.