A gigabyte is 2 to the 30th
power, or 1,073,741,824 bytes.
It can be estimated as 10 to the 9th power, or one billion
bytes. A gigabyte is 1,024
and precedes the
unit of measurement. Hard drive sizes are typically measured in
gigabytes, such as a 160GB or 250GB drive. The term gigabyte is
often often abbreviated as simply a "gig" in speech. For example, if
you have a 250GB hard drive, you could say, "I have 250 gigs of disk
space." The prefix "giga" comes from the Greek word "gigas," meaning
For a list of all the different units of measurements,
this Help Center article.