Data Size Converter

How it works

Enter a size and pick its unit; the table shows the same quantity in every unit, updating as you type. Decimal units (kB, MB, GB, TB) count powers of 1000. Binary units (KiB, MiB, GiB, TiB) count powers of 1024. Values show up to six significant digits.

Why a 1 TB drive shows about 931 GiB

Drive manufacturers use decimal units, so a 1 TB drive holds one trillion bytes. Operating systems traditionally count in binary, so the same drive shows about 931 GiB. Both numbers describe the same physical capacity in different units, the same way a mile and a kilometer describe one distance. Nothing is missing, despite what the shopping-cart math suggests.

Bits versus bytes

The lowercase b is bits and the uppercase B is bytes, eight bits each. Network speeds are quoted in bits per second (Mb/s), because networking equipment moves bits, while file sizes are quoted in bytes. A 300 Mb/s connection moves at most 37.5 MB per second, and protocol overhead eats into even that.

Where the names came from

Software spent decades using KB to mean 1024 bytes, which is neither the decimal meaning nor an honest round number, and the collision caused real bugs. The IEC introduced the binary prefixes (KiB, MiB, GiB) so each name could mean one thing. When a spec or a disk label matters, read the prefix literally: kB is 1000 bytes and KiB is 1024.