GB can be interpretted two ways:
Way one
1024MB where each MB = 1024KB = where each KB = 1024 bytes and each byte = 8 bits.
Therefore 1 GB = 8 589 934 592 bits
Way two
1000 MB where each MB = 1000 KB = where each KB = 1000 bytes and each byte = 8 bits.
Therefore 1 GB = 8 000 000 000 bits.
The OS will measure actual number of bits (as that's the useful number of storage) and will report sizes using way one. Hard Disk manufactures will measure in way two as they can sell the drive as bigger with less bits (cheaper to make).
So assuming that you have a 320 GB HDD measured in way two you have:
320 * 1000 * 1000 * 1000 * 8 bits = 2560000000000 bits.
Moving that to way two is 2560000000000 / 1024 / 1024 / 1024 / 8 bits = 298.02 GB.
So the total formatted size of your HDD is 298.02 GB.
However being a Dell the drive will be split into three.
1st section – couple of hundred megs – diagnostics tools.
2nd section – probably 10 – 15gb – recovery partition.
3rd section – os install section – whatever is left.
So 298.02 – 10(ish) gives 283(ish) GB – roughly what you have.
A windows 7 install is about 5GB, then you have the rest of the stuff dell sticks on there (with this being a home system I'm guessing AV, some office stuff, probably adobe reader, drivers and apps installs, etc).
Also when the data is stored on the disk it is stored in blocks that may be bigger than the file size so some space is wasted there as well (dont worry about this!).
So yeah the numbers work out about right!
However if you reply to my email I can check what the factory fitted to the system to be sure. (Dont post your service tag here!).
(Also I would say don't delete the diags partition – you may need that, you could maybe delete the restore partition but only if you have all the media, windows etc. I wouldn't bother and would suggest leaving it – it will make you life easier!).
Hope this helps!
David.
