Volumetric flow rate calculator
Bead cross-section × speed is the plastic your hotend must melt every second — this uses the same stadium bead model as your slicer, so the number matches what it actually extrudes, and shows how much headroom your hotend has left. Need the ceiling first? The max print speed calculator works the same formula backwards, and ringing from fast corners is what the pressure advance calculator tunes out.
0 mm³/s
current volumetric flow
| Flow limit (after material) | – |
| Headroom | safe– |
| Max speed at these settings | – |
| Peak flow over the move | – |
| Average flow over the move | – |
How to use
Enter the layer height, line width and speed from your slicer — as absolute millimetres or as a percentage of your nozzle, the two stay in sync — and pick your hotend, or your printer if you don't know the hotend's melt rate (whichever you touched last wins; Custom… is always there for measured values). The cross-section is the stadium bead model slicers use, not a plain rectangle, so flow runs a few percent lower than the naive height × width × speed. The result card shows the flow you are actually asking for; the headroom row shows it as a percentage of the limit after the material derating — safe below 80%, near limit from 80–100% (little margin left), over limit above 100% (the hotend cannot melt fast enough — expect under-extrusion, weak layers and skipped steps). The max-speed row reverses the formula: the fastest speed your hotend allows at these layer/width settings. The last two rows are the accel-aware reality check: over a short move the printer never reaches the nominal speed, so peak and average flow stay well below the nameplate figure.
Material matters
Max flow is a property of the hotend and the filament — the preset values are PLA-style numbers, and the material select above derates the limit for you. Rough community guidance behind the factors:
- PLA — flows easiest; quoted max-flow numbers are usually measured with PLA.
- PETG — typically 10–30% lower max flow on the same hotend; likes it slower.
- ABS / ASA — close to PLA when printed hot, but the limit drops fast if you print cold.
These are starting points only — run a max-flow test on your own setup before trusting the headroom number at the edge.