SizeMe calculates CD/DVD space requirements. SizeMe makes it possible to scan a directory and compare it to how many floppy/zip/CD-R/DVD-discs you need. It tries to fill each disc up as much as possible, and gives you the result on each disc. Drag'n'Drop support so you can simply drag the Disc into Nero (or any other preferred burning software) and it will add the maximized disc Customizes disks as you select.
