"Jethro" <Wilson@somewhere.org> wrote in message
news:f2npt2dn8gsnvmbiqpuoua0obdtklu426l@4ax.com...
> On Thu, 22 Feb 2007 10:05:40 +1100, "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, and
> why? And if usable space turns out to be less than that, then why?
>

"40gb" = 40 000 000 000 bytes
= 40 000 000 000 ÷ 1024 = 39 062 500 kb
= 39 062 500 ÷ 1024 = 38 147 mb
= 38 147 ÷ 1024 = 37.25 gb

Windows will report 37.25 gb if the whole drive is formatted to one
partition (many PCs use 3gb+ for a recovery partition). With 12% for system
restore, around 1gb for pagefile and 1gb for hibernate files and 15% free so
defrag will work well, you don't end up with much usable space!!

-Jeepers Creepers