Jethro <Wilson@somewhere.org> wrote
> Rod Speed <rod.speed.aaa@gmail.com> wrote
>> Jethro <Wilson@somewhere.org> wrote

>>> I notice there is always a great disparity between stated hard
>>> drive capacity and actual usable capacity after formatting.

>> Not if you use the right maths.

>>> Is there a chart or other paper anywhere showing maybe comparisons of
>>> this between drives, and maybe an explanation of why and how it happens?

>> The main problem is that the hard drive manufacturers state the size
>> in decimal GBs, 1,000,000,000 bytes because that is the SI standard.
>> Its often shown in binary GBs in the OS, 1,073,741,824 bytes.

> Okay - then please tell me. If a hard drive is stated to be say 40GB,
> then how much usable space after formatting is to be expected,

Varys with the formatting, FAT32 or NTFS etc.

> and why?

Because the file structures are different with the different formatting.

> And if usable space turns out to be less than that,

No it doesnt except due to the space lost in the last cluster.

> then why?

Because files arent always big enough to fill the last cluster.

>> You also lose a much smaller amount in the file structures, directorys etc.