# How is the E argument calculated for a given G1 command?

I'm working on building a tool to generate G-code (a simpler slicer), and I'm trying to calculate how much filament should be extruded per movement.

Is there a standard calculation for this? Something like:

``layer height * flow % * extruder diameter * distance ``

How does Cura calculate this?

## 1 Answer

Basically, all movements are (small) straight lines, the volume of a straight line is easily calculated as you already guessed.

To calculate the volume to be extruded you multiply the following parameters:

• the layer height (h)
• flow modifier (e.g. as pertectage) (SF)
• extruder nozzle diameter (d)
• distance of the straight line (l)

With this volume you can calculate how much filament you need to extrude. To get the length (thus the length defined by the `E` parameter), divide the obtained volume by surface area of your used filament by:

• π * (filament radius)2 or alternatively π /4 * (filament diameter)2

To sum up, the value of E is given by: enter image description here">