On 21 Feb, 22:48, Jethro <Wil...@somewhere.org> wrote:
> I notice there is always a great disparity between stated hard drive
> capacity and actual usable capacity after formatting.
>
> 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?
>
> Thanks
>
> Jethro

the relationship between a megabyte( 2^20) and an approximation of the
megabyte, (10^6), is a factor of 1.048576.

Meaning that to get from one to the other, you multiply or divide by
1.048576


A megabyte is 1,048,576 bytes. The Approximation is 1,000,000.

Somtimes one is called the binary megabyte and the other the decimal
megabyte, but it's not a different number system. The approximation or
decimal megabyte is just using 10^ instead of 2^.

The 10^6 figure is a smaller unit.. So more of it are used to equal a
corresponding amount of the the 'binary megabyte', which is a larger
unit.

"they say" that Hard Drive marketting people use the 'decimal
megabyte' because it sounds better, larger numbers.

The 'decimal megabyte' uses the mathemetical term Mega correctly,
since mathematically, Mega=10^6

A Kilobyte is 2^10
Megabyte is 2^20
Gigabyte is 2^30

So a megayte is 1024 kilobytes.
A gigabyte is 1024 megabytes e.t.c.

The mathematical notation just uses thousands.
Mega = 10^6
Giga=10^9
http://physics.nist.gov/cuu/Units/prefixes.html
e.t.c.