An exabyte (derived from the SI prefix exa-) is a unit of information or computer storage equal to one quintillion (one long scale trillion) bytes. It is commonly abbreviated EB.

Because of irregularities in definition and usage of the kilobyte, the exact number in common practice could be either of the following:

• 1,000,000,000,000,000,000 bytes - 1000⁶, or 10¹⁸.
• 1,152,921,504,606,846,976 bytes - 1024⁶, or 2⁶⁰. This capacity may be expressed unambiguously as an exbibyte.

As of 2004, exabytes of data are almost never encountered in a practical context. For example, the total amount of printed material in the world is estimated to be around a fifth of an exabyte. However, one may hear of 16 exabytes (exbibytes) of address space when discussing 64-bit architectures.

Exabyte is also the name of a company that manufacturers computer data backup products. Exabyte Corporation is based in Boulder, Colorado.

As of February 2005, no one has made a tape capable of holding a full exabyte.

petabyte << exabyte << zettabyte

See also

• Binary prefix