Why do Storage devices(Hard Drives/USB Drives) show less space than advertised?

           Why do Storage devices(Hard Drives/USB Drives) show less space than advertised?

Hey everyone,
             I'm here to answer a most common FAQ.  I bought a 16 GB USB flash drive a few days ago, when i plugged it in. It showed the available storage space as 14.95 GB. I really thought the manufacturers are fooling us by wrongly advertising  or there might be some error which needs to be calibrated. Guess what? As always i was wrong. Sorry, my bad :(. 
You all might have also wondered about the same thing at least at one point or another or maybe not. You can see this for yourself right now. Take any digital storage device(USB Flash Drive, Hard drive, SD card etc.,) and plug it into a windows computer. You will notice the available space is slightly less than advertised. For instance, If you plug a 16 GB USB drive like my case you will notice 1.4 GB missing as advertised.

Now Why does this happens? What causes it? Why do windows and some older versions of mac do show less storage space than advertised? Are manufacturers fooling us? all sorts of questions will be answered below.

Now Why does this happen?

  Long answer short is that common programs including Windows system BIOS and some older versions of Mac uses binary number systems where 1 GB amounts to 1024 MB rather than 1000 MBs which leads to the error in storage devices. Now before trying to understand the reason behind this error we should understand about the MBs, GBs and TBs- the basic units of storage devices.

Understanding the basics of KB,MB and GB:

 The smallest entity used to measure the capacity of storage devices is bytes of which 1 byte accounts for 8 bits(1byte = 8bits), a cluster of 1000 bytes makes up a kilobytes(1KB = 1000 bytes). Now, you will be having the most common question which you have learned in your computer basics that 1KB = 1024 bytes but sorry people you are just confused like the millions of people around the world. :(

Comparing Decimal and Binary System:

Note: The amount of disk space consumed by a file system depends upon the file system itself. Many popular programs and operating system including Microsoft Windows, System BIOS, FDISK and some old versions of macOS follows the binary number system(with base 2). There is a reason behind that too, but lets stay within the scope of the article and it is convenient within the computer to organize things in the powers of 2. Therefore 1kB contains 2^10 = 1024 bytes. 

However there is a problem the metric system that we use for measuring storage devices  are all decadic.. which means they are expressed in powers of 10 (not 2). The prefix system is great for decimal sytem, but in the binary system the one that Windows and many other programs use the terms :- Kilo, Mega, Giga, Tera doesn't exist. Since, they work with powers of 2 they use slightly different prefixes to explain large numbers, For example 1024 bytes makes up 1 kibibytes(KiB) and 1024 KiB equals to 1 Mebibytes(MiB). See the below table to understand this concept better.

 A lot of confusions arises from how these units are represented or printed. People mistakenly use the units of Decimal and Binary System Interchangeably. For Example: The unit 'Kibibytes(KiB)' is causally represented as 'KB' which is mistaken for Kilobytes the same goes for MiB and MB(Mebibyte and Megabyte), GiB and GB(gibibyte and Gigabyte) etc,.

Is manufacturers fooling us by wrongly advertising?

The answer is NO..!

It is the manufacturers(and not the programs like windows and system BIOS) who correctly label these prefixes mega and giga i.e; they use powers of 10 to express storage quantities while labeling the products.

Take a look at this back side packet of a 1GB USB flash Drive.

In the label it is clearly mentioned that 1GB = 1,000,000,000 bytes. The best way to check the true capacity of the storage device is to check the number of "bytes" intead of MBs and GBs. It could be quite confusing but for manufactures 1MB = 1000 KB, for windows 1MB = 1024KB(which is actually 1024 Kibibytes). This is why when you plug a storage device in your computer the storage value is quite less than advertised.

Below is a table showing the anomaly of storage capacity as they appear on windows:

Note that windows could update their user interface to decimal system and display the storage capacity in the future. That's what AppleOS has already done.

So next time when you purchase a storage device and it shows low space than advertised don't stew chill dude. Just check the packaging and verify it's capacity as 1TiB or 1TB. Better still, check the number of 'bytes' the hard drive can handle. At this point you can easily calculate its correct total capacity. If it's a windows machine you have plugged it is bound to show less space than advertised. Don't freak out, that you have been cheated of 50 GBs by the manufacturers they are just trying to be honest.

FACT FLASH:

     Seagate the best and largest manufactures of External Hard Drives has promised to launch a 60TB SSD(Solid State Drive) at 2017. Which will be the world's highest capacity solid state drive capable of storing over 12000 movies and 400 million photos.

Photo via +SeagateTechnology 

I guess this blog was helpful in understanding the anomaly in storage devices If you have any doubts regarding the concepts explained feel free to leave a comment..!

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