Browser-only OrcaSlicer calibration tool

Max Volumetric Speed Calculator

Turn the speed at which a flow test started to under-extrude into the max volumetric speed (mm³/s) for your filament profile. Enter the nozzle, line width and layer height the test was sliced with, add the speed where the extrusion broke down, and get the ceiling plus the equivalent speed limit at other layer heights and line widths. Every calculation runs in this page — nothing you type is uploaded, stored or sent to a server.

1 — Geometry the test was sliced with

These three values decide the cross-section of the extruded bead, and the volumetric flow is that cross-section multiplied by speed. Read them from the profile that sliced the test, not from what you intend to print later.

The nozzle that printed the test. It anchors the comparison table of line widths and the plausibility notes below.

Print settings → Quality → Line width, as sliced for the test. The usual starting point is close to the nozzle diameter.

Print settings → Quality → Layer height. A taller layer needs more flow at the same speed, so the ceiling drops.

2 — Where the extrusion broke down

Read the speed from the point on the test where walls started to come out thin, gappy or glossy-wet with gaps between the lines — the last value that still printed cleanly is the safer reading.

The tower is labelled with the speed for each band, so enter the band where it went wrong.

Flow-ramp tests are already in mm³/s.OrcaSlicer’s own Max volumetric speed test ramps the volumetric flow directly and labels the tower in mm³/s. If that is the test you printed, the value you read off the tower is already the answer and there is nothing to convert — this page is for tests that ramp print speed in mm/s.

Result

Enter the nozzle diameter, line width, layer height and the speed where the extrusion broke down, then selectCalculate max volumetric speed.

How the max volumetric speed calculation works

Volumetric flow is the volume of plastic pushed through the nozzle per second. It is the cross-section of the extruded bead — line width multiplied by layer height — multiplied by how fast the nozzle travels. So the speed at which a test starts to under-extrude converts straight into a flow ceiling:

max volumetric speed = line width × layer height × print speed

Worked example: a 0.40 mm nozzle sliced with a0.42 mm line width and a0.20 mm layer height, on a tower that started to under-extrude at 150 mm/s:0.42 × 0.20 × 150 = 12.60 mm³/s.

The same relation solved the other way gives the comparison tables: at a fixed ceiling, a taller layer or a wider line leaves less speed available, so the limit falls.

Running the test the number comes from

  1. Slice a flow or speed test tower with the line width and layer height you want the profile to use in real prints, and note both values.
  2. Print it in the filament you are calibrating. Temperature matters: a tower printed 10 °C cold will fail early and give you a ceiling that is too low.
  3. Find the band where the walls stopped being solid — thin, gappy or rough with gaps between the lines. Step one band back to the last clean value.
  4. Enter that speed here with the nozzle, line width and layer height.
  5. Save the starting cap into the filament profile, then print a real part and check the top surface and the walls before raising it.

What the number does and does not tell you

  • It is a limit for one hotend, nozzle and filament.Swap the nozzle, the extruder or the spool and the ceiling moves. A 0.6 mm nozzle on the same hotend has a different ceiling from the 0.4 mm you measured.
  • It caps speed, not quality. OrcaSlicer uses max volumetric speed to slow moves down so the hotend can keep up. It does not fix ringing, poor cooling or a bad first layer.
  • The failure point is a soft edge, not a cliff. Prints usually look acceptable a little below the value where the tower went wrong, which is why the page suggests a starting cap instead of the tested maximum.
  • A suspiciously high reading means the test, not the hotend. If the tower never actually broke down, or was sliced with a different line width or layer height than you entered, the arithmetic will happily produce a number that no profile should use.
  • Mechanical problems come first. A partial clog, a worn nozzle, a slipping extruder or a filament path with too much drag will all show up as an early flow limit. Fix those before recording a ceiling.

Saving the value in OrcaSlicer

Max volumetric speed lives in the filament profile: Filament settings → Filament → Max volumetric speed. Because it belongs to the filament, it follows the spool across printers and AMS slots. Start at the suggested cap, print something with long fast moves, and only then decide whether to raise it.

Flow ratio and max volumetric speed are separate calibrations that work together: flow ratio sets how much plastic a given move asks for, and max volumetric speed decides how fast the hotend is allowed to be asked for it. Calibrate flow ratio first, then the ceiling.

Frequently asked questions

What is max volumetric speed in OrcaSlicer?

It is the flow ceiling stored in the filament profile, in mm³/s. OrcaSlicer compares the flow each move would need (line width × layer height × speed) against that ceiling and slows the move down when it would exceed it.

Where do I read the failure speed from?

From the band on the test where the walls stopped being solid. The last band that printed cleanly is the safer reading, because the failure point is a gradual loss of extrusion rather than a clean break.

What if my test ramps flow instead of speed?

Then there is nothing to convert. OrcaSlicer’s built-in Max volumetric speed test ramps the flow in mm³/s and labels the tower with those values, so the number on the tower is already the ceiling. This calculator is for tests that ramp print speed in mm/s.

Is the suggested starting cap a measured value?

No. It is the tested ceiling reduced by 85% as a rule of thumb, so that the profile has headroom for the faster moves the slicer generates elsewhere. Treat it as a starting point and confirm it on a real print.

Does the calculator send my numbers anywhere?

No. The calculation is plain arithmetic that runs in this page, and no value you type is stored, logged or transmitted.

Put the ceiling to work

The number only counts once it is saved in the filament profile and reused on every spool of that material.

How to save and reuse filament profilesFlow ratio calculatorHow OrcaSlicer’s speed limits interact