A pebibyte (PiB) is a unit of data storage equal to 250 bytes, or 1,125,899,906,842,624 bytes. Like kibibyte (KiB) and mebibyte (MiB), pebibyte has a binary prefix to remove any ambiguity when compared to the multiple possible definitions of a petabyte.
A pebibyte is slightly larger than a petabyte (PB), which is 1015 bytes (1,000,000,000,000,000 bytes); a pebibyte is roughly 1.1259 petabytes. A pebibyte is 1,024 tebibytes. 1,024 pebibytes make up a exbibyte.
Due to historical naming conventions in the computer industry, which used decimal (base 10) prefixes for binary (base 2) measurements, the common definition of a petabyte could mean different numbers. When computer engineers first began using the term kilobyte to refer to a binary measurement of 210 bytes (1,024 bytes), the difference between binary and decimal measurements was roughly 2%. As file sizes and storage capacities expanded, so did the difference between the two types of measurements — a pebibyte is more than 11% larger than a petabyte. Using pebibyte to refer specifically to binary measurements helps to address the confusion.
NOTE: For a list of other units of measurement, view this Help Center article.