Hard drive manufacturers market drives in terms of decimal (base 10) capacity. In decimal notation, one megabyte (MB) is equal to 1,000,000 bytes, and one Gigabyte (GB) is equal to 1,000,000,000 bytes.
Programs such as FDISK, system BIOS, and Windows use the binary (base 2) numbering system. In the binary numbering system, one megabyte is equal to 1,048,576 bytes, and one gigabyte is equal to 1,073,741,824 bytes.
Simply put, decimal and binary translates to the same amount of storage capacity. Lets say you wanted to measure the distance from point A to point B. The distance from A to B is one kilometer or .621 miles. It is the same distance, but it is reported differently due to the measurement.
Capacity Calculation Formula
Decimal capacity / 1,048,576 = Binary MB capacity
Example:
A 40 GB hard drive is approximately 40,000,000,000 bytes (40 x 1,000,000,000).
40,000,000,000 / 1,048,576 = 38,162 megabytes
In the table below are examples of approximate numbers that the drive may report.
