Kilobyte

Last updated
Multiple-byte units
Decimal
Value Metric
1000kB kilobyte
10002MB megabyte
10003GB gigabyte
10004TBterabyte
10005PBpetabyte
10006EBexabyte
10007ZBzettabyte
10008YByottabyte
10009RBronnabyte
100010QBquettabyte
Binary
Value IEC Memory
1024KiBkibibyteKBkilobyte
10242MiBmebibyteMBmegabyte
10243GiBgibibyteGBgigabyte
10244TiBtebibyteTBterabyte
10245PiBpebibyte–
10246EiBexbibyte–
10247ZiBzebibyte–
10248YiByobibyte–
–
–
Orders of magnitude of data

The kilobyte is a multiple of the unit byte for digital information. The International System of Units (SI) defines the prefix kilo as a multiplication factor of 1000 (103); therefore, one kilobyte is 1000 bytes. [1] The internationally recommended unit symbol for the kilobyte is kB. [1]

Contents

In some areas of information technology, particularly in reference to random-access memory capacity, kilobyte instead typically refers to 1024 (210) bytes. This arises from the prevalence of sizes that are powers of two in modern digital memory architectures, coupled with the coincidence that 210 differs from 103 by less than 2.5%. A kibibyte is 1024 bytes. [1]

Definitions and usage

Decimal (1000 bytes)

In the International System of Units (SI) the metric prefix kilo means 1000 (103); therefore, one kilobyte is 1000 bytes. The unit symbol is kB.

This is the definition recommended by the International Electrotechnical Commission (IEC). [2] This definition, and the related definitions of the prefixes mega (1000000), giga (1000000000), etc., are most commonly used for data transfer rates in computer networks, internal bus, hard drive and flash media transfer speeds, and for the capacities of most storage media, particularly hard disk drives, [3] flash-based storage, [4] and DVDs. It is also consistent with the other uses of the metric prefixes in computing, such as CPU clock speeds or measures of performance.

The international standard IEC 80000-13 uses the term "byte" to mean eight bits (1 B = 8 bit). Therefore, 1 kB = 8000 bit. One thousand kilobytes (1000 kB) is equal to one megabyte (1 MB), where 1 MB is one million bytes.

Binary (1024 bytes)

The term 'kilobyte' has traditionally been used to refer to 1024 bytes (210 B). [5] [6] [7] The usage of the metric prefix kilo for binary multiples arose as a convenience, because 1024 is approximately 1000. [8]

The binary interpretation of metric prefixes is still prominently used by the Microsoft Windows operating system. [9] Binary interpretation is also used for random-access memory capacity, such as main memory and CPU cache size, due to the prevalent binary addressing of memory.

The binary meaning of the kilobyte for 1024 bytes typically uses the symbol KB, with an uppercase letter K. The B is sometimes omitted in informal use. For example, a processor with 65,536 bytes of cache memory might be said to have "64 K" of cache. In this convention, one thousand and twenty-four kilobytes (1024 KB) is equal to one megabyte (1 MB), where 1 MB is 10242 bytes.

In December 1998, the IEC addressed such multiple usages and definitions by creating prefixes such as kibi, mebi, gibi, etc., to unambiguously denote powers of 1024. [10] Thus the kibibyte, symbol KiB, represents 210  bytes = 1024 bytes. These prefixes are now part of IEC 80000-13. The IEC further specified that the kilobyte should only be used to refer to 1000 bytes. The International System of Units restricts the use of the SI prefixes strictly to powers of 10. [11]

Use of term

Data examples

See also

Related Research Articles

The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness.

A binary prefix is a unit prefix that indicates a multiple of a unit of measurement by an integer power of two. The most commonly used binary prefixes are kibi (symbol Ki, meaning 210 = 1024), mebi (Mi, 220 = 1048576), and gibi (Gi, 230 = 1073741824). They are most often used in information technology as multipliers of bit and byte, when expressing the capacity of storage devices or the size of computer files.

<span class="mw-page-title-main">Gigabyte</span> Unit of digital information

The gigabyte is a multiple of the unit byte for digital information. The prefix giga means 109 in the International System of Units (SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB.

Giga ( or ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or 1,000,000,000). It has the symbol G.

Kilo is a decimal unit prefix in the metric system denoting multiplication by one thousand (103). It is used in the International System of Units, where it has the symbol k, in lowercase.

The kilobit is a multiple of the unit bit for digital information or computer storage. The prefix kilo- (symbol k) is defined in the International System of Units (SI) as a multiplier of 103 (1 thousand), and therefore,

The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix mega is a multiplier of 1000000 (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes of information. This definition has been incorporated into the International System of Quantities.

The megabit is a multiple of the unit bit for digital information. The prefix mega (symbol M) is defined in the International System of Units (SI) as a multiplier of 106 (1 million), and therefore

IEC 60027 is a technical international standard for letter symbols published by the International Electrotechnical Commission (IEC), comprising the following parts:

An order of magnitude is usually a factor of ten. Thus, four orders of magnitude is a factor of 10,000 or 104.

<span class="mw-page-title-main">1024 (number)</span> Natural number

1024 is the natural number following 1023 and preceding 1025.

A unit prefix is a specifier or mnemonic that is prepended to units of measurement to indicate multiples or fractions of the units. Units of various sizes are commonly formed by the use of such prefixes. The prefixes of the metric system, such as kilo and milli, represent multiplication by positive or negative powers of ten. In information technology it is common to use binary prefixes, which are based on powers of two. Historically, many prefixes have been used or proposed by various sources, but only a narrow set has been recognised by standards organisations.

File size is a measure of how much data a computer file contains or, alternately, how much storage it consumes. Typically, file size is expressed in units of measurement based on the byte. By convention, file size units use either a metric prefix or a binary prefix.

IEEE 1541-2002 is a standard issued in 2002 by the Institute of Electrical and Electronics Engineers (IEEE) concerning the use of prefixes for binary multiples of units of measurement related to digital electronics and computing. IEEE 1541-2021 revises and supersedes IEEE 1541–2002, which is 'inactive'.

ISO 80000 or IEC 80000, Quantities and units, is an international standard describing the International System of Quantities (ISQ). It was developed and promulgated jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It serves as a style guide for using physical quantities and units of measurement, formulas involving them, and their corresponding units, in scientific and educational documents for worldwide use. The ISO/IEC 80000 family of standards was completed with the publication of the first edition of Part 1 in November 2009.

The JEDEC memory standards are the specifications for semiconductor memory circuits and similar storage devices promulgated by the Joint Electron Device Engineering Council (JEDEC) Solid State Technology Association, a semiconductor trade and engineering standardization organization.

In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multiples of bits per second (bit/s) and bytes per second (B/s). For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second (Mbit/s).

This timeline of binary prefixes lists events in the history of the evolution, development, and use of units of measure which are germane to the definition of the binary prefixes by the International Electrotechnical Commission (IEC) in 1998, used primarily with units of information such as the bit and the byte.

In digital computing and telecommunications, a unit of information is the capacity of some standard data storage system or communication channel, used to measure the capacities of other systems and channels. In information theory, units of information are also used to measure information contained in messages and the entropy of random variables.

An order of magnitude is generally a factor of ten. A quantity growing by four orders of magnitude implies it has grown by a factor of 10000 or 104. However, because computers are binary, orders of magnitude are sometimes given as powers of two.

References

  1. 1 2 3 International Standard IEC 80000-13 Quantities and Units – Part 13: Information science and technology, International Electrotechnical Commission (2008).
  2. ↑ Prefixes for Binary Multiples Archived 2007-08-08 at the Wayback Machine — The NIST Reference on Constants, Units, and Uncertainty
  3. ↑ 1977 Disk/Trend Report Rigid Disk Drives, published June 1977
  4. ↑ SanDisk USB Flash Drive Archived 2008-05-13 at the Wayback Machine "Note: 1 megabyte (MB) = 1 million bytes; 1 gigabyte (GB) = 1 billion bytes."
  5. ↑ Kilobyte – Definition and More from the Free Merriam-Webster Dictionary Archived 2010-04-09 at the Wayback Machine . Merriam-webster.com (2010-08-13). Retrieved on 2011-01-07.
  6. ↑ Kilobyte | Define Kilobyte at Dictionary.com Archived 2010-09-01 at the Wayback Machine . Dictionary.reference.com (1995-09-29). Retrieved on 2011-01-07.
  7. ↑ Definition of kilobyte from Oxford Dictionaries Online Archived 2006-06-25 at the Wayback Machine . Askoxford.com. Retrieved on 2011-01-07.
  8. ↑ "Prefixes for binary multiples". iec.ch. International Electrotechnical Commission. Archived from the original on 25 September 2016. Retrieved 1 October 2016.
  9. 1 2 "Determining Actual Disk Size: Why 1.44 MB Should Be 1.40 MB". Support.microsoft.com. 2003-05-06. Archived from the original on 2014-02-09. Retrieved 2014-03-25.
  10. ↑ National Institute of Standards and Technology. "Prefixes for binary multiples". Archived from the original on 2007-08-08. "In December 1998 the International Electrotechnical Commission (IEC) [...] approved as an IEC International Standard names and symbols for prefixes for binary multiples for use in the fields of data processing and data transmission."
  11. ↑ Le Système international d’unités [The International System of Units](PDF) (in French and English) (9th ed.), International Bureau of Weights and Measures, 2019, p. 143, ISBN   978-92-822-2272-0 . "The SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000 bits and not 1024 bits). The names and symbols for prefixes to be used with powers of 2 are recommended as follows: kibi Ki 210 [...]"
  12. ↑ "SA400 minifloppy". Swtpc.com. 2013-08-14. Archived from the original on 2014-05-27. Retrieved 2014-03-25.
  13. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2011-06-08. Retrieved 2011-06-24.{{cite web}}: CS1 maint: archived copy as title (link)
  14. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2011-04-23. Retrieved 2011-06-24.{{cite web}}: CS1 maint: archived copy as title (link)
  15. ↑ "How OS X and iOS report storage capacity". Support.apple.com. 2013-07-01. Archived from the original on 2014-03-04. Retrieved 2014-03-25.
  16. ↑ "How Mac OS X reports drive capacity". Apple Inc. 2009-08-27. Archived from the original on 2009-12-22. Retrieved 2009-10-16.
  17. ↑ "3G/GPRS data rates". Vodafone Ireland. Archived from the original on 26 October 2016. Retrieved 26 October 2016.
  18. ↑ "Data Measurement Scale". AT&T. Retrieved 26 October 2016.[ permanent dead link ]
  19. ↑ "Internet Mobile Access". Orange Romania. Archived from the original on 26 October 2016. Retrieved 26 October 2016.
  20. ↑ "Our Customer Terms" (PDF). Telstra. p. 7. Archived (PDF) from the original on 10 April 2017. Retrieved 26 October 2016.
  21. ↑ "Vulgata Clementina". pater noster qui es in cælis sanctificetur nomen tuum adveniat regnum tuum fiat voluntas tua sicut in cælo et in terra panem nostrum supersubstantialem da nobis hodie et dimitte nobis debita nostra sicut et nos dimittimus debitoribus nostris et ne nos inducas in tentationem sed libera nos a malo
  22. ↑ Poe, Edgar Allan. "The Cask of Amontillado" – via Project Gutenberg.
  23. ↑ Dickens, Charles (July 1, 1998). "Great Expectations" – via Project Gutenberg.
  24. ↑ Melville, Herman (July 1, 2001). "Moby Dick; Or, The Whale" – via Project Gutenberg.
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