I didn’t know you could do this so easily. Linux file systems reserve space for the super user. But that can just be a waste of 5% of your useful space, particularly on removable drives. Anyway I was reading about fdisk and mkfs over on InstallingANewHardDrive and discovered that if you want to reserve no space (i.e. have all your space available for a user) then you can just run the following command:

  tune2fs -m 0 /dev/sdb1

Where /dev/sdb1 is the partition you are modifying. Handy!