Backup Size Smaller than Original Size

I am backing up a drive that is 490GB. When I backup to my 2TB backup drive the backed up size is only 473GB. Why is the backed up data smaller than the original? During the backup process I select every available location to back up from . I do not understand what is being missed or not backed up.

Hi Cameronfox,

If you are using WD Backup, please know that there are few files that cannot be backed by the WD Backup. You can refer the link mentioned below to know such file types.

You can access the data backed up by the WD Backup in order to find out the files that are not being backed up by the application. You can refer the steps mentioned in the link given below access the files backed up by WD Backup.

I don’t know what software you used for backup but many backup software use compression.