The following table shows the general size of data in computer system.

Unit Size What it means
Bit (b) 1 or 0 Short for "binary digit", after the binary code (1 or 0) computers use to store and process data.
Byte (B) 8 bits Enough information to create an English letter or number in computer code. It is the basic unit of computing.
Kilobyte (KB) 1,024 or 210 bytes From "thousand" in Greek. One page of typed text is 2KB.
Megabyte (MB) 1,024KB or 220 bytes From "large" in Greek. The complete works of Shakesperare total 5MB. A typical pop song is about 4MB.
Gigabyte (GB) 1,024MB or 230 bytes From "giant" in Greek. A two-hour film can be compressed into 1-2GB.
Terabyte (TB) 1,024GB or 240 bytes From "Monster" in Greek. All the categolued books in America's Library of Congress total 15TB.
Petabyte (PB) 1,024TB or 250 bytes All leters delivered by America's postal service in 2011 amount to around 5PB. Google processes around 1PB every hour.
Exabyte (EB) 1,024PB or 260 bytes Equivalent to 10 billion copies of The Economist.
Zettabyte (ZB) 1,024EB or 270 bytes The total amount of information in existence in 2011 is to be around 1.2ZB.
Yottabyte (YB) 1,024ZB or 280 bytes Current too big to imagine.

References & Resources

  • The Economist - A Special Report on managing information"Data, data everywhere"