Icon Converter

I tried multiple sizes of multiple formats and it never produced and ICO file. There is, however, a very fast, free, high quality, and easy to use Chrome extension that leaves this piece of garbage in the dust. (Remember the part where I said it's free.)

way too many bugs - freezes up - and does not work very well

I couldn't get this app to produce any icon files. Look for another option. I installed Penteract Icon FIle Converter. It worked as advertised.

Drag and Drop doesn't result in the production of icons. Nothing I did, resulted in Icons being produced from jpg's of any size or shape.