Why KB and KiB are different — and why it matters
Disk drives advertise GB, but your OS reports GiB. This article explains the 1000-vs-1024 divide.
The short version: KB = 1000 bytes, KiB = 1024 bytes. They are not the same.
In 1998, the IEC standardised the binary prefixes precisely to fix the confusion: KiB, MiB, GiB, TiB, PiB for 1024-based quantities. kB, MB, GB, TB, PB stay SI-compliant at 1000-based.
Why does this matter in practice? Three scenarios:
1. Disk drives are advertised in TB (10¹² bytes). Your operating system reports them in TiB (2⁴⁰ bytes), so the same disk appears smaller. 2. Networking is measured in kilobits per second (kb/s, lowercase b for bits) — 1 kb = 1000 bits. Your download in MB/s means megabytes per second — 1 MB = 8 × 1000 = 8000 bits per byte. 3. RAM has always been sold and reported in binary GB (GiB formally), so the OS matches.
The "4.7 GB" DVD is actually 4.7 GB in SI bytes, which equals about 4.38 GiB. A "1 TB" SSD is about 0.91 TiB.
If you want to compare properly, use the converters on this site. They handle both decimal and binary prefixes correctly.