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Multiples of bytes
Value Metric
1000 kB kilobyte
10002 MB megabyte
10003 GB gigabyte
10004 TB terabyte
10005 PB petabyte
10006 EB exabyte
10007 ZB zettabyte
10008 YB yottabyte
1024 KiB kibibyte KB kilobyte
10242 MiB mebibyte MB megabyte
10243 GiB gibibyte GB gigabyte
10244 TiB tebibyte
10245 PiB pebibyte
10246 EiB exbibyte
10247 ZiB zebibyte
10248 YiB yobibyte

The terabyte is a multiple of the unit byte for digital information. The prefix tera represents the fourth power of 1000, and means 1012 in the International System of Units (SI), and therefore one terabyte is one trillion (short scale) bytes. The unit symbol for the terabyte is TB.

1 TB = 1000000000000bytes = 1012bytes = 1000gigabytes.

A related unit, the tebibyte (TiB), using a binary prefix, is equal to 10244 bytes. One terabyte is about 0.9095 TiB. Despite the introduction of these standardized binary prefixes, the terabyte is still also commonly used in some computer operating systems, primarily Microsoft Windows, to denote 1099511627776 (10244 or 240) bytes for disk drive capacity.[1][2]


Early if not first usage of terabyte in selected production products:

  • Supercomputer memory: 2005 (binary usage)[3]
  • Hard disk drives: 2007 (decimal usage)[4]
  • Tape drives: 2010 (decimal usage)[5]
  • Motherboard Memory: 2011 (binary usage) [6]

Illustrative usage examples[edit]

Examples of the use of terabyte to describe data sizes in different fields are:

  • Library data: The U.S. Library of Congress Web Capture team claims that as of March 2014 "the Library has collected about 525 terabytes of web archive data" and that it adds about 5 terabytes per month.[7]
  • Online databases: Ancestry.com claims approximately 600 TB of genealogical data with the inclusion of US Census data from 1790 to 1930.[8]
  • Computer hardware: Hitachi introduced the world's first one terabyte hard disk drive in 2007.[9]
  • Historical Internet traffic: In 1993, total Internet traffic amounted to approximately 100 TB for the year.[10] As of June 2008, Cisco Systems estimated Internet traffic at 160 TB/s (which, assuming to be statistically constant, comes to 5 zettabytes for the year).[11] In other words, the amount of Internet traffic per second in 2008 exceeded all of the Internet traffic in 1993.
  • Social networks: As of May 2009, Yahoo! Groups had "40 terabytes of data to index".[12]
  • Video: Released in 2009, the 3D animated film Monsters vs. Aliens used 100 TB of storage during development.[13]
  • Usenet: In October 2000, the Deja News Usenet archive had stored over 500 million Usenet messages which used 1.5 TB of storage.[14]
  • Encyclopedia: In January 2010, the database of Wikipedia consists of a 5.87 terabyte SQL dataset.[15]
  • Climate science: In 2010, the German Climate Computing Centre (DKRZ) was generating 10000 TB of data per year, from a supercomputer with a 20 TB memory and 7000 TB disk space.[16]
  • Audio: One terabyte of audio recorded at CD quality contains approx. 2000 hours of audio. Additionally, one terabyte of compressed audio recorded at 128 kB/s contains approx. 17,000 hours of audio.
  • The Hubble Space Telescope has collected more than 45 terabytes of data in its first 20 years of observations.[17]
  • The IBM computer Watson, against which Jeopardy! contestants competed in February 2011, has 16 terabytes of RAM.[18]

See also[edit]


  1. ^ How operating systems report drive capacity, Seagate Inc.
  2. ^ Windows disk space using TB as a binary value, from Seagate.com
  3. ^ Gara, et. al., (2005, March/May). Overview of the Blue Gene/L system architecture. IBM JRD, p.195-212 "32 TB of total memory" (p.203)
  4. ^ Hitachi Introduces 1-Terabyte Hard Drive
  5. ^ expected in H1 2010 with 1.5TB - 3TB storage (updated)
  6. ^ New Intel Server Board to Hold 1 TB of RAM
  7. ^ "Web Archiving FAQs: How large is the Library's archive?". Library of Congress. Archived from the original on 31 July 2014. Retrieved 7 April 2011. 
  8. ^ "Ancestry.com Adds U.S. Census Records". CBS News. 2006-06-22. 
  9. ^ "Hitachi Introduces 1-Terabyte Hard Drive". PC World. 2007-01-07. Retrieved 2008-09-15. 
  10. ^ Swanson, Bret (2007-10-03). "Discovery Institute's Technology Blog: An exabyte here, an exabyte there". disco-tech. Retrieved 2013-04-14. 
  11. ^ White, Bobby (2008-06-16). "Cisco Projects Growth To Swell for Online Video". The Wall Street Journal. 
  12. ^ "Yahoo! Groups Blog". 2009-05-09. 
  13. ^ IRENE THAM (2009-04-08). "Taking a monster shit; Massive computer power was needed to create the 3-D movie Monsters Vs Aliens.". The Straits Times. The 3-D movie used up close to 100 terabytes of disk space and more than 40 million hours of rendering. 
  14. ^ "Usenet Sale: Sounds to Silence?". 2000-10-25. Retrieved 2009-10-13. It's loaded with 500 million postings .... [and has] ballooned to over 1.5 terabytes 
  15. ^ "Data dumps – Meta". Meta.wikimedia.org. Retrieved 2013-04-14. 
  16. ^ [1][dead link]
  17. ^ "NASA – NASA – The Hubble Story". Nasa.gov. 2010-04-29. Retrieved 2013-04-14. 
  18. ^ "It’s Technical, Dear Watson – The "Jeopardy!" playing computer’s feeds and speeds". ibmsystemsmag.com. February 2011. Retrieved 2013-07-04.