Since the popular rise of the personal computer users have asked the time old question: “Why does my 100 gigabyte hard drive only give me 93 gigabytes when I format it?”

The answer lies with the 2nd use of the word “gigabyte” in that sentence.  In reality when we say “gigabyte” we don’t mean 1,000,000,000 bytes, we mean 1,073,741,824 bytes because computers work in powers of two (binary).   This informal assumption works fine, until we mix the two units:  Hard drive manufacturers label their products using the metric system (gigabyte being metric), computers use binary multiples.

As far back as 1998 the International Electrotechnical Commision established binary symbols and prefixes to clarify this and eliminate the ambiguity:

Unit Abbreviation Number of Bytes
kibibyte KiB 1,024
mebibyte MiB 1,048,576
gibibyte GiB 1,073,741,824
tebibyte TiB 1,099,511,627,776

15 years later, I think it’s time has finally come. We’re standardizing on these units here at A-Team Systems, and have been seeing them being used in technical media and blogs recently as well.

So let’s give up the good fight we’ve had with trying to get hard drive manufacturers to label their products the way they are actually used, and instead simply acknowledge that they use an entirely different measuring system.

Goodbye MB, GB, TB … hello MiB, GiB, TiB!

One Response to “Goodbye MB/GB/TB, Hello MiB/GiB/TiB”

  1. Alfredo Harvey Mac Kissack

    And we, end users are being scammed.
    Because I went to purchase a 2 (TWO) TB disk, namely
    2×1024×1024×1024×1024 = 2,199,023,255,552 bytes
    and I received a 2,000,398,934,016-byte piece
    which divided by 1024*1024*1024*1024 = 1099511627776 bytes
    equals 1.81935223191977 (the new notation) TiB

    So, I didn’t get a true 2 TiB drive, which is what I was aimig.

    And it has become an immense confusion because all measurements
    are now full of decimals preventing us to know what we are getting.


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