The petabyte is a multiple of the unit byte for digital information. The prefix 'peta' indicates the fifth power of 1,000, therefore 1 petabyte is one quadrillion (short scale) bytes, or 1 billiard (long scale) bytes. The unit symbol for the petabyte is PB.
1PB = 1,000,000,000,000,000 B
The units go up as per the following chart