When determining file size, should we use the actual file size or the file size on disk? File size on disk tends to be slightly bigger, and quite larger in one instance (a previous small project was 5.45 MB total, 57.0 MB on disk!)

I guess is the first size, the one telling the true space.

(is in spanish and a bit darker)
Because if is the last one ... Well I need to rework all the proyect xD

Actually I'm going for Size on Disk. As you can see here, my EXE file for a game I'm working on is 33kb on disk. 

Wow, this got interesting quick! I'm trying to use TIC-80 as an engine, and it's not terrible in filesize (if you manipulate a lot under the hood. Trying to set the background for the map? Depending on the tile, +20k. And that's adding one tile!) 3k size, 4k on disc, and I've made some progress. I'll even have sound (hopefully!)