Flow Rate Calibration

We have all been there: you print a part that looks great, but when you try to assemble it, nothing fits. Or maybe you are dealing with rough top surfaces that ruin the look of an otherwise perfect print. Often, the culprit isn't your machine mechanics—it's just how much plastic is flowing through the nozzle.

Calibrating your Flow Rate (or Extrusion Multiplier) ensures you are getting the optimal volumetric flow from your hot end. This simple adjustment allows you to produce strong, dimensionally accurate prints that fit together perfectly every time.

Calibrating Flow Rate

Flow rate calibration is the process of matching your slicer's theoretical math to your printer's physical output.

Fortunately, this is one of the easier calibrations to perform. It can be completed in less than 30 minutes, and the difference in print quality is immediately noticeable.

Step 1: Download our test file and import it in your slicer

To start, download the standard Calibration Cube and open it in your preferred slicer (Cura, PrusaSlicer, etc.).

Step 2: Modify your existing slicers settings to match the list below

We need to create a specific testing environment to get an accurate reading. Change your settings to match these parameters:

• Line Width: 1.2X Nozzle Diameter (Ex. 0.4mm Nozzle = 0.48mm Line Width)
• Layer Height: 0.2mm (or set to your normal printer layer height)
• Vase (Spiralize) Mode: Enabled (This forces a single wall and usually sets infill to 0%)
• Print Speed: Set to your normal wall printing speed

Step 3: Save the gcode and begin print

Send the file to your printer. Watch the first layer to make sure it goes down smoothly, then let it finish.

Step 4: Measure the results

After the print has finished and cooled, carefully remove it from the build surface.

Using your digital calipers, take measurements of the wall thickness on each of the four sides.

Step 5: Enter parameters and calculate

Take your four measurements and enter them into the calculator below.

If you are using vase mode, the "number of walls" is one. Note that some users prefer to run this test with two or more walls instead of vase mode; feel free to experiment with both, however, we prefer using a single wall for clarity.

Step 6: Update flow rate

Take the value you just calculated and update the Flow Rate (or Extrusion Multiplier) setting in your slicer profile.

Step 7: Verify the results

Rerun the test print with your updated flow rate. Ideally, if your slicer is set to one wall and a line width of 0.48mm, your physical measurement should now also be exactly 0.48mm.

Conclusion

That's it—your extruder is now fully calibrated! By taking a few minutes to tune this setting, you will see better top surfaces and parts that click together with satisfying precision.