Q: Information On Hard Drive Size And Partitioning

A: Storage drive manufacturers measure storage drive capacity using the decimal system (base 10), so 1 gigabyte (GB) is calculated as 1,000,000,000 bytes. The capacity of the storage drive in the computer is measured using the decimal system. This is what is displayed on the computer.

Microsoft Windows Operating systems use the binary system (base 2) of measurement. In binary, 1 GB is calculated as 1,073,741,824 bytes. This difference in how the decimal and binary numeral systems measure a GB is what causes a 4 GB storage drive to appear as 3.7 GB when detailed by an operating system, even though the storage drive still has 4 billion bytes, as reported. This difference will be seen if you look at how the computer summarizes the capacity of the computer’s storage drive. The important point to understand is that the available storage capacity is the same no matter which system is used and that no storage space is missing.

The hard drive in the computer, like all storage drives, uses some capacity for formatting, so actual capacity available for applications will be less. In addition, other factors, such as pre-installed systems or other software and media, will also use part of the available storage capacity on the drive.

Example: An advertised 100 GB will be displayed as 93.13 GB by Windows, but inspecting the properties of the hard drive within the Device Manager will indicate its full size.

Note: The hard drive may be partitioned from the factory to include a factory restore option, or may be partitioned to create a seperate drive for storage of personal data. The combined storage space of all partitions will indicate total available space.