« Back to Glossary Index

gigabyte GBGigabyte is a unit of digital information storage. The prefix giga means 10^9, therefore a gigabyte is about 1,000,000,000 bytes. Gigabyte is abbreviated as GB with an uppercase “B” to prevent confusing it with bit, which is in lowercase “b”. You may hear people refer to “gigs” instead of saying “gigabytes”. This is a common slang term when referring to storage device sizes.

Today’s hard drives typically are 250 – 500 gigabytes, but it is becoming more common to see 1000 GB hard drive capacities which are equivalent to 1 terabyte (TB). It is in hard drive (or flash drive) sizes that the difference between the decimal definition of Giga and binary definition becomes obvious. Consumers are often confused when a 250 GB hard drive will report (via an operating system) a number different than 250 GBs. For example, a 250 GB hard drive actually has 268,435,456,000 bytes (or it may read in terms of megabytes as 256,000 MB). This is because a gigabyte in binary (the system used for computers) is actually 2 to the 30th power or 1,073,741,824.

The difference is that computes work on a base 2 system (binary) whereas the decimal system is base 10. However it is common among many to use the systems interchangeably. Normally this doesn’t introduce any major issues for non-technical users (i.e. anyone not programming or building computers that need to know the difference) as the decimal measure is a good approximation of the binary.

The International Electrotechnical Commission has recommended alternative prefixes to use for the binary system to avoid this common substitution. The change has not caught on in general use even though many industry standards committees have endorsed the changes.

Gigabyte is also found on the computer’s RAM; indicating the random memory or data it can access directly in any random order. For example a computer may have access 2 GB video RAM and 16 GB of system RAM.

« Back to Glossary Index