Real Hard disk Capacity

Hard disk drive capacity is that manufacturers assume that kilobyte (KB), megabyte (MB), gigabyte (GB) and terabyte (TB) are different things from what they really are, making you to have a hard disk drive with less capacity than advertised. This problem is known by several names, like “rounding”, “formatted capacity vs. unformatted capacity”, etc. Some people even wrongly assume that the operating system is the villain behind the vanishing of space, but the truth of the matter is that the hard drive manufacturers are the one to blame, as they announce their products with a capacity higher than the real drive capacity.

Unit	Symbol	Base 2	Base 10
Kilo	K	2^10	10^3
Mega	M	2^20	10^6
Giga	G	2^30	10^9
Tera	T	2^40	10^12
Peta	P	2^50	10^15
Exa	E	2^60	10^18

For example, hard disk drive manufacturers assume that 1 GB equals to 1 billion (10^9) bytes, while in fact 1 GB equals to 1,073,741,824 (2^30) bytes.
Let’s take a real example, Seagate/Maxtor/Samsung hard disk drive with “250 GB”. It is announced as being a 250 GB hard disk drive, having 488,397,168 sectors. With this number of sectors we can easily find out that the capacity of this hard disk drive is of 250,059,350,016 bytes, or 232.88 GB and not 250 GB. So here is why your 250 GB hard drive is only formatted with 232 GB: it IS a 232 GB hard drive!

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