Hard drive space is measured in bytes. Other units are simply built on the term byte, such as kilobyte (1000 bytes), megabyte (1000 kilobytes or 1 million bytes), gigabyte (1000 megabytes or 1...
You can get almost any size in gigabytes you want in a hard drive. 50, 100, 500, whatever you feel they make it. In fact there are now hard drives that are larger than gigabytes, they are called...