I’ve been in the industry for over 20 years, and I’m just now learning this. I knew there was a disturbance in the force, but it was never enough of an issue to investigate.
Anyway. Basically, there are two ways of using Kilx within computer sizing of things.
Multiplying by 1000, as in 1000 bytes = 1 kilobyte
Using binary with an exponent of 10, like 210, which is 1024, not 1000
And depending on which you use, you’ll get different sizes. And that’s why we’ve often seen disappearing sizes in real life compared to advertisements—they were using the large number instead of the little one!
A kilo is 1000.
A kibi is 1024.
The world is a strange place.
The Wikipedia article on kibibyte. More