Max print speed & layer height calculator
Your hotend can only melt so much plastic per second — this turns that limit into a hard speed ceiling. Pushing flow on a freshly calibrated extruder? Verify with the rotation distance calculator and keep dimensional accuracy with shrinkage compensation.
0 mm/s
maximum print speed
| Layer height check | – |
| Recommended line width | – |
| Cross-section extruded | – |
| Recommended sustained speed | – |
| Effective speed on a short move | – |
How it works
Volumetric flow is the budget: speed = flow ÷ bead cross-section, where the cross-section is the stadium shape slicers actually extrude: lh × (lw − lh) + π·lh²/4. The flow presets are measured max-flow values in the style of Ellis' max volumetric flow test— your real number depends on material and temperature, so test yours. Layer height follows the Prusa KB rule: at most 80% of the nozzle diameter (above that the new bead does not bond to the layer below), and practically at least 25% of it. Line width prints best at 100–120% of the nozzle. Source: Prusa KB — Layers and perimeters.
The presets are PLA numbers — the material select derates the flow limit (PETG and TPU melt slower, so their speed ceiling is lower). The recommended sustained speed spends only 80% of the max flow, leaving headroom for temperature swings and material variation, and the short-move row shows the speed your acceleration actually allows on a move of the given length.
Frequently asked questions
What is volumetric flow?
The maximum volume of molten plastic your hotend can deliver per second, in mm³/s. Print speed, line width and layer height spend that budget, so it sets a hard ceiling on how fast you can print.
What is a typical max flow for a stock hotend?
An E3D V6-class hotend manages about 11 mm³/s; high-flow designs like the Dragon HF, Rapido or Mosquito reach 24–30 mm³/s. Your real number depends on material and temperature, so measure it with a max-flow test.
What is the maximum layer height for a 0.4 mm nozzle?
The Prusa rule caps layer height at 80% of the nozzle diameter — 0.32 mm for a 0.4 mm nozzle — and practically at least 25% of it (0.10 mm). Above the cap the new bead does not bond properly to the layer below.
Why do my prints fail at the calculated max speed?
The calculator assumes the hotend sustains the entered flow; real flow drops with lower temperatures and some materials. Test your actual max flow and keep some headroom below the ceiling.