Yobibyte (symbol YiB) is a unit of digital information in the binary (base‑2) prefix system. It is used to describe very large quantities of data and storage capacity. The term belongs to the family of binary prefixes that begin with kibibyte (KiB) and continue through mebi-, gibi-, tebi-, pebi-, exbi-, zebi-, and yobi-.
Definition and magnitude
A yobibyte equals 2^80 bytes. In the binary hierarchy it holds 1024 zebibytes (ZiB). In decimal terms this is approximately 1.2089 × 10^24 bytes, so a single YiB is slightly larger than one yottabyte (the SI decimal unit of 10^24 bytes).
- 1 YiB = 2^80 bytes.
- 1 YiB = 1024 ZiB.
- 1 YiB ≈ 1.2089 × 10^24 bytes ≈ 1.21 yottabytes (decimal).
History and standardization
Binary prefixes like yobibyte were formalized by international standards bodies in the late 1990s to remove ambiguity between powers of two (used in computing) and powers of ten (used in the SI system). The IEC notation (KiB, MiB, GiB, …, YiB) is now recommended for unambiguous technical communication.
Although YiB describes extremely large capacities more common in theoretical or large‑scale infrastructure planning than in everyday consumer products, the prefix provides a consistent way to report sizes as storage systems and datasets continue to grow.
Uses, importance and common confusion
Yobibytes are most likely to appear in discussions of hyperscale storage, global data archives, or very large scientific datasets. In practice, most consumer storage is described in decimal prefixes (kilobyte, megabyte, terabyte) which use powers of ten; this difference often causes confusion when comparing advertised drive sizes to reported usable capacity in operating systems. Using the IEC binary prefixes (including YiB) avoids that ambiguity.