*SUMMARY: This tip defines the following computer memory terms: kilobyte, megabyte, gigabyte, terabyte, petabyte, exabyte, zettabyte, and yottabyte.*

Computers and storage mechanisms (CD-ROMs, hard drives, USB flash drives, DVD-ROMs, Blu-ray Discs, etc.) need to hold much larger values than what a byte can hold (0-255). Thus, the terms kilobyte, megabyte, gigabyte, terabyte, petabyte, exabyte, zettabyte, and yottabyte were created to represent such large amounts of information.

The definition of a kilobyte **(KB)** is 1,024 bytes; however many people think of it as 1,000 bytes.

The definition of a megabyte **(MB)** is 1,024 kilobytes; however many people think of it as 1,000 kilobytes.

The definition of a gigabyte **(GB)** is 1,024 megabytes; however many people think of it as 1,000 megabytes.

The definition of a terabyte **(TB)** is 1,024 gigabytes; however many people think of it as 1,000 gigabytes.

The definition of a petabyte **(PB)** is 1,024 terabytes; however many people think of it as 1,000 terabytes.

The definition of an exabyte **(EB)** is 1,024 petabytes; however in some number systems it would be 1,000 petabytes.

The definition of a zettabyte **(ZB)** is 1,024 exabytes; however in some number systems it would be 1,000 exabytes.

The definition of a yottabyte **(YB)** is 1,024 zettabytes; however in some number systems it would be 1,000 zettabytes.

Why the confusion? There are two numbering systems in play. Strictly in "computerese", a base 2 system is in play, so that one kilobyte is **2 to the power of 10 bytes**, or 1024 kilobytes. However, many hardware manufacturers, including hard drive manufacturers think of a kilobyte as only 1,000 bytes, or **10 to the power of 3 bytes**.

This is the same with megabytes, gigabytes, terabytes, petabytes, exabytes, zettabytes, and yottabytes, and that is one reason why when you buy a hard drive with, for example, one terabyte, you may not be getting exactly the amount of storage room that you think!

Return to the Computer Memory Definitions page.

[MODIFIED] Six Battery Conservation Tips

What is My IP Address?

Missing the Title Bar? Menu Bar?

Bring Back the Mouse Pointer Drop Shadow

The MalekTips website was created in 1998 by Andrew Malek of Envision Programming. The page's goal is to freely disperse computer-related tips, hints, and informative articles. Tips are organized to be easy to find, and are presented clearly, in easy-to-understand language.