Kilobyte

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

The kilobyte is a multiple of the unit byte for digital information.

The byte is a unit of digital information that most commonly consists of eight bits, representing a binary number. 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.

Computer data storage technology consisting of computer components and recording media used to retain digital data

Computer data storage, often called storage or memory, is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers.

Contents

The International System of Units (SI) defines the prefix kilo as 1000 (103); per this definition, one kilobyte is 1000 bytes. [1] The internationally recommended unit symbol for the kilobyte is kB. [1]

International System of Units a system of units of measurement for base and derived physical quantities

The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, which are the second, metre, kilogram, ampere, kelvin, mole, candela, and a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system also specifies names for 22 derived units, such as lumen and watt, for other common physical quantities.

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 unit symbol k, in lower case.

In some areas of information technology, particularly in reference to digital memory capacity, kilobyte instead denotes 1024 (210) bytes. This arises from the powers-of-two sizing common to memory circuit design. In this context, the symbols K and KB are often used.

Information technology (IT) is the use of computers to store, retrieve, transmit, and manipulate data, or information, often in the context of a business or other enterprise. IT is considered to be a subset of information and communications technology (ICT). An information technology system is generally an information system, a communications system or, more specifically speaking, a computer system – including all hardware, software and peripheral equipment – operated by a limited group of users.

Definitions and usage

Base 10 (1000 bytes)

In the International System of Units (SI) the 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 drives, [3] flash-based storage, [4] and DVDs. It is also consistent with the other uses of the SI prefixes in computing, such as CPU clock speeds or measures of performance.

International Electrotechnical Commission organization

The International Electrotechnical Commission is an international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology". IEC standards cover a vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, semiconductors, fibre optics, batteries, solar energy, nanotechnology and marine energy as well as many others. The IEC also manages three global conformity assessment systems that certify whether equipment, system or components conform to its International Standards.

Mega is a unit prefix in metric systems of units denoting a factor of one million (106 or 1000000). It has the unit symbol M. It was confirmed for use in the International System of Units (SI) in 1960. Mega comes from Ancient Greek: μέγας, romanized: megas, lit. 'great'.

Giga ( or ) is a unit prefix in the metric system denoting a factor of a (short-form) billion (109 or 1000000000). It has the symbol G.

The IEC 80000-13 standard 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.

The bit is a basic unit of information in information theory, computing, and digital communications. The name is a portmanteau of binary digit.

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.

Base 2 (1024 bytes)

The kilobyte has traditionally been used to refer to 1024 bytes (210 B), a usage still common. [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] but is deprecated or obsolete in other operating systems. Metric prefixes are 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 often 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 = 1024 bytes. These prefixes are now part of the International System of Quantities. The IEC further specified that the kilobyte should only be used to refer to 1000 bytes.

Examples

See also


Related Research Articles

A binary prefix is a unit prefix for multiples of units in data processing, data transmission, and digital information, notably the bit and the byte, to indicate multiplication by a power of 2.

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 1000000000bytes. The unit symbol for the gigabyte is GB.

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 mebibyte is a multiple of the unit byte for digital information. The binary prefix mebi means 220; therefore one mebibyte is equal to 1048576bytes, i.e., 1024 kibibytes. The unit symbol for the mebibyte is MiB.

The gibibyte is a multiple of the unit byte for digital information. The binary prefix gibi means 230, therefore one gibibyte is equal to 1073741824bytes = 1024 mebibytes. The unit symbol for the gibibyte is GiB. It is one of the units with binary prefixes defined by the International Electrotechnical Commission (IEC) in 1998.

The tebibyte is a multiple of the unit byte for digital information. It is a member of the set of units with binary prefixes defined by the International Electrotechnical Commission (IEC). Its unit symbol is TiB.

The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 210, or 1024; therefore, 1 kibibyte is 1024 bytes. The unit symbol for the kibibyte is KiB.

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

The kibibit is a multiple of the bit, a unit of digital information storage, using the standard binary prefix kibi, which has the symbol Ki, meaning 210. The unit symbol of the kibibit is Kibit.

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 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.

The zebibyte is a multiple of the unit byte for digital information. It is a member of the set of units with binary prefixes defined by the International Electrotechnical Commission (IEC). Its unit symbol is ZiB.

ISO 80000 or IEC 80000 is an international standard promulgated jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).

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 article presents a timeline of binary prefixes used to name memory units, in comparison of decimal and binary prefixes for measurement of information and computer storage.

In 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 the entropy of random variables and information contained in messages.

References

  1. 1 2 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. "SA400 minifloppy". Swtpc.com. 2013-08-14. Archived from the original on 2014-05-27. Retrieved 2014-03-25.
  12. "Archived copy" (PDF). Archived (PDF) from the original on 2011-06-08. Retrieved 2011-06-24.CS1 maint: Archived copy as title (link)
  13. "Archived copy" (PDF). Archived (PDF) from the original on 2011-07-25. Retrieved 2011-06-24.CS1 maint: Archived copy as title (link)
  14. "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.
  15. "How Mac OS X reports drive capacity". Apple Inc. 2009-08-27. Archived from the original on 2009-12-22. Retrieved 2009-10-16.
  16. "3G/GPRS data rates". Vodafone Ireland. Archived from the original on 26 October 2016. Retrieved 26 October 2016.
  17. "Data Measurement Scale". AT&T. Retrieved 26 October 2016.[ permanent dead link ]
  18. "Internet Mobile Access". Orange Romania. Archived from the original on 26 October 2016. Retrieved 26 October 2016.
  19. "Our Customer Terms" (PDF). Telstra. p. 7. Archived (PDF) from the original on 10 April 2017. Retrieved 26 October 2016.