Thank you for answering, but I'm having a problem with both methods.
I googled and it sems like I have to install some libraries for a particular type of .svg or something like that, but I installed Inkscape and It's still the same so I don't know how to proceed.
The title pretty much sums it up. I'm running ImageMagick and I'm really bad at this, it took me a while to understand that I had to open convert.exe from CMD so it wouldn't close itself. I have a bunch of .svg files located at C:\Users\Cristian\Documents\Downloads\flattr-icons-master\flattr-icons ...