A kilobyte (kB) is 1000 bytes, that's what the prefix kilo means. A kibibyte (KiB) is 1024 bytes (the "bi" in the prefix means base 2 or binary). People often confuse them, but they're similar enough for smaller units, 103 ~ 210.
Oh and at first, kilobyte was used for both amounts, which is why kibibytes were introduced to fix the confusion, which perhaps was a bit late anyway.
The wobbly windows fix is appreciated