# FreBlogg

## Why do Hard Drives and USB sticks show less space than advertised ?

18:54 Posted by DurgaSwaroop

Have you always wondered why a 8GB USB drive shows less than 8GB (7.5 GB) of space and why does a 500 GB HDD shows an available space of 465GB right out of the box?
That is not because the manufacturer is cheating you or something,but it has to do with the difference in the definitions  of a GB (Giga Byte) for our computer and the manufacturer. It has to do with math.
Hate Math? We'll make it easy for you.

We generally have two kinds of base systems. A base-10 system (Decimal system) and a base-2 system (binary system). This is the root cause of the difference. The manufactures market the memory in Decimal system.
So for a marketer, 1KB = 1,000 Bytes ; 1MB = 1,000,000 Bytes ; 1 GB = 1,000,000,000 Bytes
But a computer doesn't quite understand the decimal system. It only understands binary system.
To a computer, 1 KB = 1,024 Bytes ; 1 MB = 1,048,576 Bytes ; 1GB = 1,073,741,824 Bytes

So, you can see that when they say it has a storage of 1MB, you are actually getting 48000 Bytes less and so is the case with 1GB. You are getting almost 73MB less than what your computer is expecting.
Now, when they say 500 GB, what you are actually getting is,
`500,000,000,000 / (1024 x 1024 x 1024) = 465.6 GB`

As always, Have a Happy Reading !

HDD image: http://www.flickr.com/photos/kubina/326629513/in/photostream/

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