Volumetric Flow Rate Calculator

Find your printer's maximum safe print speed based on your hotend's flow limit. Pushing past it causes under-extrusion - this tells you exactly where that limit is.

Your Setup

80% recommended - running at 100% causes intermittent under-extrusion

Results

Max safe speed (80%)

213 mm/s

At 0.2mm layer / 0.45mm line width

Hotend max flow

24 mm³/s

Theoretical max - 80% = 19.2 mm³/s

- Absolute max speed (100% flow): 267 mm/s - expect under-extrusion above this

- Each 10mm/s print speed requires 0.90 mm³/s of flow at these settings

- Increasing layer height or line width reduces max speed proportionally

What is volumetric flow rate?

Volumetric flow rate (mm³/s) is the amount of plastic your hotend can melt and push through the nozzle per second. It's the true speed limit of FDM printing - not mm/s alone.

At higher speeds, the hotend can't melt filament fast enough. The result is under-extrusion: thin, weak, or missing layers. This is called "heat limited" printing.

Formula: Max speed (mm/s) = Max flow rate (mm³/s) ÷ (layer height × line width)

A CHT (Core Heating Technology) nozzle improves flow by routing filament through three channels, increasing melt surface area by ~3×. This is why Bambu and Voron users often upgrade to CHT nozzles before pushing speeds past 150mm/s.

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