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Prefixes for multiples of bits (bit) or bytes (B)

Decimal prefix - Decimal

SI prefix - SI

{]] | class="floatright" | " | Prefixes for multiples of [[bits (bit) or bytes (B) ]] | - | { | " !colspan="3" | [[Decimal prefix | Decimal ]] | - !colspan="1" | Value !colspan="2" | [[SI prefix | SI ]] | - | 1000 | k | binary_prefix | [[kilo- | kilo ]] | - | 1000² | M | binary_prefix | [[mega- | mega ]] | - | 1000³ | G | binary_prefix | [[giga- | giga ]] | - | 1000⁴ | T | binary_prefix | [[tera- | tera ]] | - | 1000⁵ | P | binary_prefix | [[peta- | peta ]] | - | 1000⁶ | E | binary_prefix | [[exa- | exa ]] | - | 1000⁷ | Z | binary_prefix | [[zetta- | zetta ]] | - | 1000⁸ | Y | binary_prefix | [[yotta- | yotta ]] | } | { | " !colspan="5" | [[Binary prefix | Binary ]] | - !colspan="1" | Value !colspan="2" | [[IEC 80000-13 | IEC !colspan=“2” ]] | Unit prefixes for semiconductor storage capacity | Legacy ]] | - | 1024 | Ki | binary_prefix | [[kibi- | kibi ]] | K | binary_prefix | kilo | - | 1024² | Mi | binary_prefix | [[mebi- | mebi ]] | M | binary_prefix | mega | - | 1024³ | Gi | binary_prefix | [[gibi- | gibi ]] | G | binary_prefix | giga | - | 1024⁴ | Ti | binary_prefix | [[tebi- | tebi ]] | T | binary_prefix | tera | - | 1024⁵ | Pi | binary_prefix | [[pebi- | pebi ]] | center" | – | binary_prefix | binary_prefix | - | 1024⁶ | Ei | binary_prefix | [[exbi- | exbi ]] | center" | – | binary_prefix | binary_prefix | - | 1024⁷ | Zi | binary_prefix | [[zebi- | zebi ]] | center" | – | binary_prefix | binary_prefix | - | 1024⁸ | Yi | binary_prefix | [[yobi- | yobi ]] | center" | – | binary_prefix | binary_prefix | } | - | colspan=2 | {{navbar | Bit and byte prefixes | mini=1 | }} | } ===Systematic multiples - Binary prefixes=== Terms for large quantities of [[bits can be formed using the standard range of SI prefixes for powers of 10, e.g., kilo- | kilo = 10³ = 1000 (as in kilobit or kbit), mega- | mega = 10⁶ =

(as in megabit or Mbit) and giga- | giga = 10⁹ =

(as in gigabit or Gbit). These prefixes are more often used for multiples of bytes, as in kilobyte (1 kB = 8000 bit), megabyte (1 MB =

), and gigabyte (1 GB =

).

However, for technical reasons, the capacities of computer memories and some storage units are often multiples of some large power of two, such as 2²⁸ =

bytes. To avoid such unwieldy numbers, people have often repurposed the SI prefixes to mean the nearest power of two, e.g., using the prefix kilo for 2¹⁰ = 1024, mega for 2²⁰ =

, and giga for 2³⁰ =

, and so on. For example, a random access memory chip with a capacity of 2²⁸ bytes would be referred to as a 256-megabyte chip. The table below illustrates these differences.

{]] | class="wikitable" ! Symbol ! Prefix ! [[SI prefix | SI Meaning ! Binary prefix | Binary meaning ! Size difference ]] | - | k | kilo | = 1000¹ | = 1024¹ | 2.40% | - | M | mega | = 1000² | = 1024² | 4.86% | - | G | giga | = 1000³ | = 1024³ | 7.37% | - | T | tera | = 1000⁴ | = 1024⁴ | 9.95% | - | P | peta | = 1000⁵ | = 1024⁵ | 12.59% | - | E | exa | = 1000⁶ | = 1024⁶ | 15.29% | - | Z | zetta | = 1000⁷ | = 1024⁷ | 18.06% | - | Y | yotta | = 1000⁸ | = 1024⁸ | 20.89% | } In the past, uppercase ''K'' has been used instead of lowercase ''k'' to indicate 1024 instead of 1000. However, this usage was never consistently applied. On the other hand, for external storage systems (such as [[optical discs), the SI prefixes are commonly used with their decimal values (powers of 10). There have been many attempts to resolve the confusion by providing alternative notations for power-of-two multiples. In 1998 the International Electrotechnical Commission (IEC) issued a standard for this purpose, namely a series of binary prefixes that use 1024 instead of 1000 as the main radix:<ref name=“IEC80000_2005”/>

{]] | class="wikitable" ! Symbol ! Prefix ! colspan=3 | binary_prefix | - | Ki | kibi, ''binary kilo'' | 1 [[kibibyte (KiB) ]] | 2¹⁰ bytes | 1024 B | - | Mi | mebi, ''binary mega'' | 1 [[mebibyte (MiB) ]] | 2²⁰ bytes | 1024 KiB | - | Gi | gibi, ''binary giga'' | 1 [[gibibyte (GiB) ]] | 2³⁰ bytes | 1024 MiB | - | Ti | tebi, ''binary tera'' | 1 [[tebibyte (TiB) ]] | 2⁴⁰ bytes | 1024 GiB | - | Pi | pebi, ''binary peta'' | 1 [[pebibyte (PiB) ]] | 2⁵⁰ bytes | 1024 TiB | - | Ei | exbi, ''binary exa'' | 1 [[exbibyte (EiB) ]] | 2⁶⁰ bytes | 1024 PiB | } The [[JEDEC memory standards | JEDEC memory standard JESD88F notes that the definitions of kilo (K), giga (G), and mega (M) based on powers of two are included only to reflect common usage.<ref name=“JEDEC_2018_Terms”/>

Binary prefix