Calculating trace length

Is there a function in Fritzing to show/report the length of a given trace? I’m playing around with making a little PCB heater plate and I’d like to have the length so I can use it in calculating power/current, etc.

Hello Andrei!

Well, it depends upon what you want to measure. If you just want to measure a length, in core parts, under ‘tools’, there is a ruler part. Drag that part into the pcb view and you can measure anything with it. It’s like using a ruler in real life to measure things on paper, move it around and note measurements…

If you want to measure area (width * length) of a pcb, in core parts, under pcb parts, there is a part called "Copper Fill Blocker’. It is used to designate an area where no copper traces should be, a keep-out area. It’s a rectangle area that can be sized and moved as needed, and it’s current width & length are reported in the inspector view.

Hope this helps,

I’ve got the ruler, but the trace has lots of turns in it, so I was wondering if there was a way to pull that info out from somewhere.

I believe all of the coordinates (bend points) are stored in the sketch file, so it should be possible to calculated it. Nothing I know of currently provides access to it though. Once the sketch (.fzz) file is unzipped, the .fz file inside is xml, which could be processed to locate the needed information. xml is straight forward, but I don’t have good documentation of the data structure used by Fritzing. I have manually looked through the content (it is a text file) to see where something went wrong, but that is not the same as using a program to extract specific details (based on something like a wire id).

Aside from the Fritzing problems, something to consider is how much heat are you considering? Too much (and I don’t know what too much is!) and the copper will unlaminate from the FR4 base I expect. I don’t think pcbs make particularly good heaters :slight_smile: . If you want to consider @microMerlin 's suggestion of parsing the fz file for the track info (which uses python and lxml to parse the xml in the parts files) would be one place to start. I haven’t done any parsing of the .fz files, but that is where I would start if I needed to.