Binary prefix

Prefixes for multiples of bits (b) or bytes (B)
Decimal Value Metric 1000 k kilo 10002 M mega 10003 G giga 10004 T tera 10005 P peta 10006 E exa 10007 Z zetta 10008 Y yotta	Binary Value JEDEC IEC 1024 K kilo Ki kibi 10242 M mega Mi mebi 10243 G giga Gi gibi 10244 Ti tebi 10245 Pi pebi 10246 Ei exbi 10247 Zi zebi 10248 Yi yobi

In computing, a binary prefix is a specifier or mnemonic that is prepended to the units of digital information, the bit and the byte, to indicate multiplication by a power of 1024.
The computer industry has historically used the units kilobyte, megabyte, and gigabyte, and the corresponding symbols KB, MB, and GB, in at least two slightly different measurement systems. In citations of main memory (RAM) capacity, gigabyte customarily means 1073741824bytes. As this is the third power of 1024, and 1024 is a power of 2 (2¹⁰), this usage is therefore referred to as a binary prefix.
In most other contexts, the industry uses the multipliers kilo, mega, giga, etc., in a manner consistent with their meaning in the International System of Units (SI), namely as powers of 1000. For example, a 500gigabyte hard disk holds 500000000000bytes, and a 100megabit per second Ethernet connection transfers data at 100000000bit/s. In contrast with the binary prefix usage, this use is described as a decimal prefix, as 1000 is a power of 10.
The ambiguity of using the same unit prefixes for two different representations within the same industry has caused some confusion. Starting around 1998, several standards and trade organizations approved standards and recommendations for a new set of binary prefixes that refer unambiguously to powers of 1024. Accordingly, the SI prefixes should only be used in the decimal sense, even when referring to data storage capacities: kilobyte and megabyte denote one thousand bytes and one million bytes respectively (consistent with SI), while new terms such as kibibyte, mebibyte and gibibyte, having the symbols KiB, MiB, and GiB, denote 1024bytes, 1048576bytes, and 1073741824bytes, respectively.^[1]

Contents 1 History 1.1 Main memory 1.2 Disk drives 1.3 Information transfer and clock rates 1.4 Standardization of dual definitions 2 Inconsistent use of units 2.1 Deviation between powers of 1024 and powers of 1000 2.2 Consumer confusion 2.3 Legal disputes 2.3.1 Willem Vroegh v. Eastman Kodak Company 2.3.2 Orin Safier v. Western Digital Corporation 2.3.3 Cho v. Seagate Technology (US) Holdings, Inc. 3 Unique binary prefixes 3.1 Early suggestions 3.2 IEC prefixes 3.3 Adoption by IEC and NIST 3.4 Specific units of IEC 60027-2 A.2 and ISO/IEC 80000 3.5 Other standards bodies and organizations 3.6 Dissent 4 Current practice 4.1 Operating systems 4.2 Software 4.3 Computer hardware 4.3.1 Computer memory 4.3.2 Hard disk drives 4.3.3 Flash drives 4.3.4 Floppy drives 4.3.5 Optical discs 4.3.6 Tape drives and media 4.3.7 Data transmission and clock rates 4.4 Websites and government agencies 5 See also 6 Definitions 7 References 8 Further reading 9 External links