Definition

gigabyte

Contributor(s): Stacey Peterson and Sarah Wilson

A gigabyte -- pronounced with two hard Gs -- is a unit of data storage capacity that is roughly equivalent to 1 billion bytes. It is also equal to two to the 30th power or 1,073,741,824 in decimal notation. Giga comes from a Greek word meaning giant. Werner Buchholz is credited with coining the term byte while helping design IBM's 7030 Stretch, the first transistorized supercomputer, in 1956.

A gigabyte, which uses the abbreviation GB, has been a common unit of capacity measurement for data storage products since the mid-1980s. In recent years, however, terabytes of storage have become the more common unit of storage capacity measurement, especially for hard disk drives (HDDs) and solid-state drives (SSDs).

Cloud providers and hardware vendors still often refer to storage capacity costs in terms of pennies per gigabyte, and flash SSDs and HDDs in the hundreds of gigabyte range are common.

How many gigabytes in a …

Data capacity measurements that are larger than a gigabyte include the following:

  • A terabyte is equal to 1,024 gigabytes.
  • A petabyte is equal to 1,048,576 gigabytes.
  • An exabyte is equal to 1,073,741,824 gigabytes.
Data storage measurements

Measurements that are smaller than a gigabyte are:

  • A megabyte -- 1,024 megabytes equal a gigabyte.
  • A kilobyte -- 1,048,576 kilobytes equal a gigabyte.
  • A byte -- 1,073,741,824 bytes equal a gigabyte.

Visualizing the size of a gigabyte

A typical DVD holds 4.7 GB of data. A typical laptop or desktop computer contains 16 GB of random access memory.

In more concrete terms, one gigabyte is equal to:

  • 250 downloaded songs;
  • 6,180 emails sent and receive;
  • 250 10-megapixel photos;
  • 50,000 average emails with no attachments;
  • 3,333 average emails with a standard attachment;
  • 5 hours of a standard definition movie; and
  • 353 one-minute YouTube videos.
Storage capacity examples

Difference in how consumer technology and other fields measure it

Two standards are used to measure the number of bytes in a gigabyte: base-10 and base-2. The base-10 definition of gigabyte uses the decimal system to show that 1 GB is equal to 109 bytes, or 1 billion bytes. Today, most storage manufacturers and consumers use the base-10 standard to define a gigabyte.

Computers typically use the base-2 or binary form of measurement. Base-2 measures 1 GB as equal to 1,073,741,824 bytes. A gigabyte is sometimes referred to as a gibibyte in this model. The discrepancy between the base-10 and base-2 measurements wasn't substantial at first. However, it became more pronounced as vendors started manufacturing storage media with more capacity.

Base-2 vs. Base-10 definition

History of the term

The first gigabyte-capacity hard drive was the IBM 3380, which was introduced in 1980. The IBM 3380 packaged two 1.26 GB hard disk assemblies in a refrigerator-sized cabinet. Pricing ranged from $81,000 to $142,000, depending on the configuration.

When PCs were first introduced, HDDs were relatively small in terms of data capacity, and they were quite expensive. The IBM Personal Computer XT, released in 1983, was the first PC with a built-in hard drive as a standard feature. It originally came with a 10 megabyte (MB) or 20 MB hard drive. In 1991, the first 1 GB drives became available with a price tag of nearly $3,000.

From there, hard drive capacity grew rapidly. When Hitachi brought out the first 1 TB drive in 2007, the company noted that it took 35 years for HDDs to reach 1 GB, and 14 years to get to 500 GB. The first 1 TB drives appeared only two years later. Today, HDDs are available with 14 TB of storage, and SSDs can hold as much as 100 TB of storage.

Gigabyte vs. gigabit

A bit, which is short for binary digit, is the smallest unit of computer data. A bit has a single binary value that is either 0 or 1. Computers generally are designed to store data and execute instructions in bit multiples called bytes. In most computer systems, there are eight bits in a byte and 8,589,934,592 bits in a gigabyte.

A byte, and by extension a gigabyte, describes data at rest. Computer memory and storage are typically measured in bytes. In many computer architectures, a byte is the smallest addressable unit of memory. For instance, an 820 MB hard drive holds 820 million bytes of data.

A bit, and by extension a gigabit, refers to data in motion. For example, gigabits are used to describe data transfer rates, such as network throughput and internet connection speeds.

Gigabyte-size storage options and pricing

There are several types of storage media available that provide gigabyte range capacity, and those capacities can vary dramatically. Some of the most commonly used storage types that provide capacity in this range are HDDs, flash drives, memory cards, USB memory sticks, Blu-ray discs and DVDs.

Price per gigabyte varies among vendors and types of storage media. However, across all vendors and storage types, prices have been falling year over year. For example, the average price per gigabyte of an HDD in 2000 was nearly $8, according to IDC, while it had dropped to 3.5 cents per gigabyte by 2017. The year-over-year decline in the average price per gigabyte for HDDs has slowed significantly in recent years.

Cost of a GB of storage

For years, flash drives have had a higher price per gigabyte than HDDs. However, that's changed recently as SSD capacity has increased and prices have dropped. The average price per gigabyte for SSDs is approaching parity with HDDs.

This was last updated in July 2018

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Do you think the price per gigabyte of storage will continue to drop? Why or why not?
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I do think the price of storage will continue to drop--for both magnetic and solid-state media.

For spinning disk, new techs like shingled magnetic recording (SMR) lets disk makers cram more data into the same space by laying it the surface at an angle. And other techniques, like HGST's use of helium instead of air in the disk enclosure, allows stacking of more platters to increase capacity.

For solid state, watch for TLC NAND flash to start to show up in enterprise flash products. TLC puts three bits of data in each flash cell (vs. one for SLC and two for MLC), upping the capacity of solid-state devices considerably.
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Why is this even a question? Of course it will continue to drop. Technology advances in a way that pushes costs continually downward, and that includes the costs of storage. The only likely reasons for this to change are an issue in manufacturing or the introduction of a new method of data storage - the price-per-Gigabyte of Solid State Drives, for example, remains higher than conventional drives. Even so, overall storage prices will continue moving downwards.
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I have to agree with James here; this is like asking if PCs are going to get faster or mobile phones are going to get more powerful. 

Let's turn it around -- if you think that the price for gigabyte *isn't* going to drop, whyever do you think that?
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