The difference between Gigabytes and Gibibytes and why it matters

This might once happened to you too:
You plugged in your new 1TB drive and in the Windows explorer it showed up as this:

This always bothered me, because when I buy a 1TB drive I want to have 1.000GB not 931GB. Then I noticed that this happens to every drive I plug in, and when I check them on my MacBook it shows up as an 1.000GB drive. So there must be an error on the Operating System?

Actually Windows is able to show the correct size of the Drive, you can see that if you open the properties tab of the drive:

In the picture you can see that is says ~ 1.000.000.000.000 bytes next to Capacity which is indeed one terra byte. But why does Windows than says right next to it 931GB when it should be 1TB?

It narrows down to the difference between a Gigabyte and a Gibibyte.

GIBIBYTE? What is that?
You ask yourself now. While Gigabytes are based on 10 (10², 10³ etc..). A Gibibyte is based on 2. That means a 10³ is 1000 but 2³⁰ is 1024. this now may be a small difference, but with larger numbers it the gap gets larger too.

I cannot answer you the question why Windows is displaying the number like that, but at least you know why.