Also formatting floppies in OS X is a bit hit-and-miss. It won't do the part where it goes back and eliminates bad blocks. You also don't get the 100% same full capacity for some reason. Also, as soon as you browse a floppy in the OS X finder, a considerable amount of the disk is used up by OS X hidden files. This is why it's best to write-protect any disks you mount in OS X.

I would definitely recommend formatting all of your disks on an old Mac, or using pre-Mac-formatted disks. It is possible to avoid some hidden files by NOT opening the disk in the Finder. Using terminal to do everything works nicely for this. Also, terminal can show you hidden files using "ls -a" so you can delete them and get the space back.

Of course, if you're just putting a few files on the disk that don't take up much space, the hidden files may not matter to you.

All I'm trying to say is that OS X has some problems with floppies that you should be aware of.