Data Storage converter

This converter's reference unit is the byte, and the factors show how every other unit scales from it. A bit is an eighth of a byte (0.125), a nibble is half a byte (0.5) and a decimal kilobyte (kB) is exactly 1,000 bytes. The binary units follow a different, doubling pattern: a kibibyte (KiB) is 1,024 bytes, a mebibyte (MiB) is 1,048,576 bytes, and the pattern keeps multiplying by 1,024 up through gibibyte, tebibyte and pebibyte.

The pair most people search for is gigabyte to gibibyte. Divide the decimal gigabyte's factor (1,000,000,000) by the binary gibibyte's factor (1,073,741,824) to get the multiplier: GiB = GB × 0.9313225746. Reverse it by multiplying by 1.073741824 instead.

A drive labeled "500 GB" by its manufacturer actually holds 500 × 0.9313225746 = 465.66 GiB once an operating system reports it in binary units — which is exactly why a brand-new "500 GB" drive shows up as roughly 465 GB in Windows or macOS. A 1 TB drive similarly converts to 1,000,000,000,000 ÷ 1,073,741,824 ≈ 931.32 GiB.

Storage vendors, and operating systems reporting raw disk capacity before formatting, use decimal units — kB, MB, GB, TB — because they're simple powers of 1,000 and match how the rest of the metric system scales. Memory chips, file systems and most consumer software instead report binary units — KiB, MiB, GiB — because computer memory is physically addressed in powers of two. Network engineers and database administrators move between both constantly, since a server's advertised disk size, its actual filesystem capacity and its RAM are often quoted in different systems on the same spec sheet.

The single biggest point of confusion in computing is treating a decimal unit and its binary look-alike as identical — GB and GiB, MB and MiB, kB and KiB are not the same size, and the gap grows the larger the number gets, from about 7.4% at the gigabyte scale to over 10% at the terabyte scale. A second common slip is confusing bit and byte: an uppercase B generally means byte and a lowercase b means bit, and the two differ by a factor of 8, which matters when comparing a storage size in bytes against a network speed quoted in bits.

The physical-media entries in this list are useful size references rather than everyday working units: a standard floppy disk held 1.44 MB, a CD about 700 MB, a DVD 4.7 GB and a single-layer Blu-ray disc 25 GB. Lined up together, they make it easier to picture how much a modern terabyte actually holds — about 40 Blu-ray discs' worth, or roughly 680,000 of those old 1.44 MB floppy disks.