I need to decide if 1KB means 1,000 bytes or 1,024 bytes in all of my software
I was leaning 1,024 but it looks like macOS and Windows both define KB as 1,000 these days
I want whatever people are most likely to understand
(I do not think most people know what KiB or MiB means)
It means 1000 bytes. `k` is an SI prefix (correct capitalisation is `kB`, not `KB`). 1024 bytes is a KiB.
Maybe your users don't know what it means, but using the wrong label just perpetuates their ignorance.
It starts to make a big difference once we're in the TB/TiB or PB/PiB range…
If anybody says "kibibyte" to me I reflexively punch them straight in the nose. Then I apologize and thank them for clarifying. Then I punch them again.