How big of dvd-r disks do I need for backing up ps3 games with Game Copy Wizard?

I want to back up my cod games and batman arkham asylum and some other games I have but I'm no sure how many gb of dvd-r I need. Help plz (:|||you can use dvd copy software to back up


http://www.macdvdconverter.com/mac-dvd-c鈥?/a>