Why you have ~10% less Hard Drive/USB space than the advertised space on the package?

Why do you have less hard drive / USB drive size in Windows than advertised?

Let's examine this, I recently purchase a USB stick that can hold advertised space of 32Gb of data. 

When I plugged in this USB drive and went to format this drive in Windows, I only get a reported maximum capacity of only 29.7G of space? 

This is an apparent loss of 32-29.7 = 2.3 Gigs of space! Or 6.7% of space gone.
What happened? Where did that extra space go, I didn't do anything yet.

Lets take an in-depth look into the drive info to find out. A cleaver way to do this is to use the MSINFO32.exe (Start->Run->type msinfo32) to run. Goto Components > Storage > Disks and scroll down to the General USB Disk. 

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Here we see in the reported Size is 29.71Gb or (31,905,861,120 bytes) for the USB Drive.

Advertisers are the total bytes number and treating it a normal decimal number.
By their math, dividing by 1000 to get shift of 3 places, results in this 

          31,905,861,120 bytes = 31,905,861 Kb = 31,905 Mb = ~ 32Gb ADVERTISED


But this is wrong. Bytes is NOT a decimal number. 

How many bits in byte?  Well, there are 8 bits in a byte. Each bit can either 1 or 0. A bit is called binary number. Binary is base 2, whereas decimal is base 10 because it has 10 digits {0,1,2,3,4,5,6,7,8,9}.

So to move a number by 3 places place in binary we have to divide by 1024, which is a standard agreed by International Electrotechnical Commission. 

Let's do the right math, we divide by 1024 to get shift of 3 places.

         31,905,861,120 bytes = 31,158,067.5 Kb = 30,427.8 Mb = 29.71Gb ACTUAL

Windows correctly reports the size of the hard disk/USB Flash Disk drive.

Advertisers are reporting the wrong HD/USB space. Advertiser are wrong math to when calculation Gigabyte sizes. 

So you are are loosing 2.2 Gb ~ 6.7% of space on this 32Gig HD out of the box!

This chart summarizes the amount of lost data because of bad math.

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As we can see Windows reports the actual HD/USB space correctly, and advertisers are ripping you off.
A class action lawsuit was settle by Western Digital in 2006 over HD size, that's how old this issue is and marketer's are still doing it! Sue my friends, sue.

Here's a logarithmically scaled version from Wikipedia.

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