This article describes the SI prefix peta. For other meanings, including People for the Ethical Treatment of Animals see Peta (disambiguation).

In physics and mathematics, peta (symbol: P) is a prefix in the SI system of units denoting 10¹⁵, or 1,000,000,000,000,000. For example:

1 petametre = 10¹⁵ metres

1 petasecond = 10¹⁵ seconds

Adopted in 1975, it comes from the Greek πέντε, meaning five, because it is equal to 1000⁵. (It is based on the model of tera, coming from the Greek for 'monster': tetra- is from the Greek for four and so peta, coming from penta-, misses the third letter, n, out.)

In computer science peta can sometimes mean 1 125 899 906 842 624 (1024⁵ or 2⁵⁰), instead of 1 000 000 000 000 000, especially when used to prefix the byte, giving a petabyte. To resolve this ambiguity, the term pebibyte has been suggested to mean 2⁵⁰ bytes. However, this term is not yet widely used.

See also

• SI prefix
• Binary prefix

External links

• BIPM website