An exabyte (abbreviated EB) is a unit of digital information in the International System of Units (SI) equal to 10^18 bytes. It is one of the largest commonly named prefixes used to quantify data and storage at planetary scale. The term combines the SI prefix "exa-", meaning 10^18, with "byte", the basic unit of digital information.

Size and simple conversions

To understand the magnitude of an exabyte, it helps to relate it to other, more familiar units of storage:

  • 1 exabyte = 1,000 petabytes; see the definition of the petabyte relationship: petabyte.
  • 1 exabyte = 1,000,000 terabytes — a million terabytes.
  • 1 exabyte = 1,000,000,000 gigabytes — a billion gigabytes.
  • 1,000 exabytes = 1 zettabyte; for the zettabyte scale see zettabyte.

Decimal versus binary interpretation

In computing, two different conventions are often used for large quantities. The SI (decimal) definition treats an exabyte as 10^18 bytes and is the standard in storage marketing and many scientific contexts. A different, binary-based quantity is the exbibyte (EiB), defined as 2^60 bytes (about 1.15×10^18 bytes). Because the two values are similar but not identical, technical documentation sometimes distinguishes exabyte (decimal) from exbibyte (binary).

History and origin of the term

The prefix "exa-" follows the metric tradition of using standardized prefixes to denote powers of ten. As information storage and transmission scaled up in the late 20th and early 21st centuries, names such as petabyte, exabyte and zettabyte became useful for describing datasets produced by large scientific instruments, global telecommunications, and enterprise storage systems. For a general definition of the unit and its context, see unit definition.

Uses, examples, and significance

Exabytes are used to describe aggregate volumes rather than single consumer devices. Typical examples include total annual global internet traffic, cumulative data stored in large cloud providers, or multi-year archives of scientific observatories and particle accelerators. Depending on drive size, an exabyte can represent hundreds of thousands to millions of consumer hard disks or solid-state drives. Because of its scale, the exabyte is a convenient unit for policy makers, engineers and researchers who work with "big data".

Notable distinctions

When comparing figures or procurement offers, pay attention to whether quantities use decimal (SI) exabytes or binary exbibytes — the difference can matter at very large scales. For a basic reference on the number of bytes involved in an exabyte, see bytes explained. Large-scale internet and storage statistics are commonly reported using exabytes and zettabytes to express trends and capacity at the global level.