Hard Drive manufacturers in general, define a gigabyte (abbreviated as GB) as 1 billion bytes (1,000,000,000 bytes).

Operating Systems and software utilities define a gigabyte as 1,073,741,824 bytes, which is based on an earlier way of measuring hard drive capacity. This method measures a kilobyte as 1,024 bytes rather than 1,000.

In like manner a megabyte is reported as having 1,024 X 1,024 bytes (1,048,576 bytes) rather than 1,000,000 bytes and a gigabyte as having 1,073,741,824 bytes.

Therefore a drive with a capacity of 9.1GB (or 9,100,000,000 bytes) on the label will have 7.37% less capacity when expressed in Gigabytes, 4.86% less capacity when expressed in Megabytes, or 2.4% less capacity when expressed in Kilobytes. For example:

9,100,000,000 decimal bytes divided by 1.048576 equals 8,678.436+ binary Kilobytes, equivalent to 8.67 MB.

Also see this 2008 thread.

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by vkr edited by dbmaven
last modified: 2008-05-05 11:15:42