Calibrating your 3D printer’s extrusion rate is a great way to really dial in the quality of your prints. I find that when using the same brand filament I can get away with calculating the extrusion once, and checking it now and again to make sure I’m fairly close. When introducing a new filament or type (like switching from PLA to PETG for example) you probably want to run this quick check again and make sure you are within a few percent for the new stuff. Calibrating is easy, and if you use Octoprint or Repetier Host or Simplify 3D and can send terminal commands, it’s just this simple:

1. Set your extruder to relative mode by issuing a M83; command
2. Next mark your filament 120 mm from the entrance to the extruder with a Sharpie
3. Then tell the printer to extrude 100mm of filament using the G1 E100 F100; command
4. Now measure the amount of filament yet to enter the extruder. I had 30mm left over. That means that 10mm is not extruded, though the machine settings think it has. So lets fix that now. (If you have 20mm yet to enter the extruder, congrats. You are done and can go get a tasty beverage.)
5. Lets find out what the current steps/mm setting is on the printer. Enter the command M503;
6. You will get a bunch of settings returned, and we are looking for the M92 output, mine was:
   M92 X80.00 Y80.00 Z400.00 E93.00
7. So lets calculate what we need here instead. I had 30mm left over. So 120mm-30mm= 90mm. My printer is pushing 90mm through, thinking it is 100. That is a 10% difference, and pretty significant. The original output above shows that my extruder steps value was 93 (see E93.00 above.) Lets calculate the correct value. A quick formula for this is (original step value x 100) / actual distance. In my case, this is (93×100)/90=103.333
8. Lets set this value as the new extruder step value with the command M92 E103.333;
9. And save those settings to the board with a M500;
10. Now your extruder should be set, so lets test! Run through the instructions again by measuring another 120mm and running the
    G1 E100 F100; command one more time and you should be pretty darn close.

Happy printing! Leave a comment below if this helped your or you have feedback on your results.