Definition

A gibibyte, abbreviated GiB, is a unit of digital information defined as exactly 2^30 bytes, which equals 1,073,741,824 bytes. It is part of the family of binary prefixes that step in powers of 1024: 1 GiB = 1024 mebibytes (MiB). The name and symbol were created to make explicit the binary nature of the quantity and avoid ambiguity with decimal-based units.

Binary versus decimal prefixes

Gibibyte is often confused with the decimal gigabyte. A gigabyte (GB) in the decimal system equals 10^9 bytes (1,000,000,000 bytes). Because 2^30 is larger than 10^9, 1 GiB ≈ 1.0737 GB, and conversely 1 GB ≈ 0.9313 GiB. The two systems coexist in computing and storage contexts, which is why the distinction matters for precise reporting.

History and standardization

To reduce confusion, standards bodies introduced explicit binary prefixes in the late 1990s. The International Electrotechnical Commission (IEC) formalized terms such as kibibyte (KiB), mebibyte (MiB) and gibibyte (GiB) so that binary multiples would have unambiguous names separate from the SI-derived decimal prefixes (kilo, mega, giga).

Uses and common examples

Operating systems and software that display memory (RAM) and some file sizes commonly use binary multiples, so a memory module labeled 4 GiB contains 4 × 2^30 bytes. Hard-drive and SSD manufacturers traditionally state capacities in decimal gigabytes (GB), which leads to the familiar observation that a drive sold as 500 GB appears as roughly 465 GiB when reported by many operating systems.

Conversions and quick reference

  • 1 GiB = 2^30 bytes = 1,073,741,824 bytes.
  • 1 GiB = 1024 MiB (mebibyte).
  • 1 GB = 10^9 bytes = 1,000,000,000 bytes ≈ 0.9313 GiB.
  • 1024 GiB = 1 tebibyte (TiB).

Practical notes

For technical precision, use GiB when referring to binary multiples and GB for decimal multiples. In everyday speech many people still use "gigabyte" to mean the binary 2^30 value, but documentation and specifications increasingly adopt the IEC binary prefixes to avoid misunderstanding. When comparing advertised disk sizes, checking whether numbers are decimal or binary will explain apparent discrepancies.