Central Axis

1 The amount of memory (measured in gigabytes or terabytes) that can be stored in a disc drive. Usually given as formatted capacity (see format operation). One gigabyte, or GB, equals one billion bytes and one terabyte, or TB, equals one thousand billion bytes. Your computer's operating system may use a different standard of measurement and report a lower capacity. In addition, some of the listed capacity is used for formatting and other functions and will not be available for data storage.