Digital data is measured in bits (a single 0 or 1) and bytes (8 bits). Larger units come in two systems that are easy to confuse. Decimal units (KB, MB, GB, TB) step by 1,000 and are used by storage manufacturers and networks. Binary units (KiB, MiB, GiB, TiB) step by 1,024 and reflect how memory is actually addressed.

This mismatch is why a "1 TB" drive shows as about 931 GiB in some operating systems — the drive uses decimal, the OS may report binary.

Handy Data storage reference points

1 byte = 8 bitsByte to bits
1 GB = 1,000 MBDecimal gigabyte
1 GiB = 1,024 MiBBinary gibibyte
1 TB ≈ 931 GiBWhy a 1 TB drive looks smaller
≈ 4 GBA typical HD movie

Supported Data storage units

Bits (bit) — The smallest unit of data, a single 0 or 1.
Bytes (B) — Eight bits, enough for one character.
Kilobytes (KB) — A kilobyte, 1,000 bytes (decimal).
Megabytes (MB) — A megabyte, one million bytes (decimal).
Gigabytes (GB) — A gigabyte, one billion bytes (decimal).
Terabytes (TB) — A terabyte, one trillion bytes (decimal).
Kibibytes (KiB) — A kibibyte, 1,024 bytes (binary).
Mebibytes (MiB) — A mebibyte, 1,048,576 bytes (binary).
Gibibytes (GiB) — A gibibyte, 1,024 mebibytes (binary).
Tebibytes (TiB) — A tebibyte, 1,024 gibibytes (binary).

This tool is provided for general information only. Verify important figures independently. · Last reviewed: August 25, 2026