kb là gì

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Not vĩ đại be confused with kilobit.

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"KByte" redirects here. For the battery electric xế hộp from Future Mobility Corporation, see Byton K-Byte.

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Multiple-byte units
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
10009 RB ronnabyte
100010 QB quettabyte
Value IEC
1024 KiB kibibyte KB kilobyte
10242 MiB mebibyte MB megabyte
10243 GiB gibibyte GB gigabyte
10244 TiB tebibyte TB terabyte
10245 PiB pebibyte
10246 EiB exbibyte
10247 ZiB zebibyte
10248 YiB yobibyte
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]

In some areas of information technology, particularly in reference vĩ đại solid-state memory capacity, kilobyte instead typically refers vĩ đại 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 kêu ca 2.5%. A kibibyte is defined by IEC 80000-13 as 1024 bytes.

Definitions and usage[edit]

Base 10 (1000 bytes)[edit]

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

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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 truyền thông media transfer speeds, and for the capacities of most storage truyền thông 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.

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

Base 2 (1024 bytes)[edit]

The term 'kilobyte' has traditionally been used vĩ đại refer vĩ đại 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]

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The binary interpretation of metric prefixes is still prominently used by the Microsoft Windows operating system.[9] Metric prefixes are also used for random-access memory capacity, such as main memory and CPU cache size, due vĩ đại 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 vĩ đại have "64 K" of cache. In this convention, one thousand and twenty-four kilobytes (1024 KB) is equal vĩ đại 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., vĩ đại unambiguously denote powers of 1024.[10] Thus the kibibyte, symbol KiB, represents 210  bytes = 1024 bytes. These prefixes are now part of the IEC 80000-13 standard. The IEC further specified that the kilobyte should only be used vĩ đại refer vĩ đại 1000 bytes. The International System of Units restricts the use of the SI prefixes strictly vĩ đại powers of 10.[11]


  • The Shugart SA-400 514-inch floppy disk (1976) held 109,375 bytes unformatted,[12] and was advertised as "110 Kbyte", using the 1000 convention.[13] Likewise, the 8-inch DEC RX01 floppy (1975) held 256,256 bytes formatted, and was advertised as "256k".[14] On the other hand, the Tandon 514-inch DD floppy format (1978) held 368,640 (which is 360×1024) bytes, but was advertised as "360 KB", following the 1024 convention.
  • Early home page computer systems would often advertise using the 1024 convention, hence the naming of the Commodore 64, Commodore 128, and the Amstrad CPC 464.
  • On modern systems, all versions of Microsoft Windows including the newest (as of 2019) Windows 10 divide by 1024 and represent a 65,536-byte tệp tin as "64 KB".[9] Conversely, Mac OS X Snow Leopard and newer represent this as 66 kB, rounding vĩ đại the nearest 1000 bytes.[15] File sizes are reported with decimal prefixes.[16]
  • As of năm 2016, the binary interpretation was still used in marketing and billing by some telecommunication companies, such as Vodafone,[17] AT&T,[18] Orange[19] and Telstra.[20]

See also[edit]


  • "Terms, Definitions, and Letter Symbols for Microcomputers, Microprocessors, and Memory Integrated Circuits" (PDF). JEDEC Solid State Technology Association. December 2002. Retrieved 22 September 2013.