# orders(7) [netbsd man page]

ORDERS(7) BSD Miscellaneous Information Manual ORDERS(7)NAME

ordersorders of magnitude--DESCRIPTION

The following table lists common multiples of bytes. Name Prefix Power of 2 Power of 10 Kilobyte kB 2^10 10^3 Megabyte MB 2^20 10^6 Gigabyte GB 2^30 10^9 Terabyte TB 2^40 10^12 Petabyte PB 2^50 10^15 Exabyte EB 2^60 10^18 Zettabyte ZB 2^70 10^21 Yottabyte YB 2^80 10^24 The following table lists common bit rates as a power of ten. Name Prefix Bit per second Byte per second Bit per second bit/s 1 0.125 Byte per second B/s 8 1 Kilobit per second kbit/s 10^3 125 Kilobyte per second kB/s 8 * 10^3 1000 Megabit per second Mbit/s 10^6 125000 Megabyte per second MB/s 8 * 10^6 1000000 Gigabit per second Gbit/s 10^9 125000000 Gigabyte per second GB/s 8 * 10^9 1000000000 Terabit per second Tbit/s 10^12 125000000000 Terabyte per second TB/s 8 * 10^12 1000000000000 The following table lists common orders of magnitude as a power of ten. Name Order Prefix Symbol Decimal Septillionth 10^-24 yocto y 0.000000000000000000000001 Sextillionth 10^-21 zepto z 0.000000000000000000001 Quintillionth 10^-18 atto a 0.000000000000000001 Quadrillionth 10^-15 femto f 0.000000000000001 Trillionth 10^-12 pico p 0.000000000001 Billionth 10^-9 nano n 0.000000001 Millionth 10^-6 micro mu 0.000001 Thousandth 10^-3 milli m 0.001 Hundredth 10^-2 centi c 0.01 Tenth 10^-1 deci d 0.1 One 10^0 - - 1 Ten 10^1 deca da 10 Hundred 10^2 hecto h 100 Thousand 10^3 kilo k 1000 Million 10^6 mega M 1000000 Billion 10^9 giga G 1000000000 Trillion 10^12 tera T 1000000000000 Quadrillion 10^15 peta P 1000000000000000 Quintillion 10^18 exa E 1000000000000000000 Sextillion 10^21 zetta Z 1000000000000000000000 Septillion 10^24 yotta Y 1000000000000000000000000SEE ALSO

units(1), strsuftoll(3), number(6)STANDARDS

There have been various attempts to standardize the set of binary prefixes. Organizations such as International Electrotechnical Commission (IEC) have proposed new prefixes such as ``kibi'', ``mebi'', ``gibi'', and ``yobi'', but the adoption has been slow at best.BSD

August 6, 2011 BSD

## Check Out this Related Man Page

UNITS(7) Linux Programmer's Manual UNITS(7)NAME

units, kilo, kibi, mega, mebi, giga, gibi - decimal and binary prefixesDESCRIPTION

Decimal prefixes The SI system of units uses prefixes that indicate powers of ten. A kilometer is 1000 meter, and a megawatt is 1000000 watt. Below the standard prefixes. Prefix Name Value y yocto 10^-24 = 0.000000000000000000000001 z zepto 10^-21 = 0.000000000000000000001 a atto 10^-18 = 0.000000000000000001 f femto 10^-15 = 0.000000000000001 p pico 10^-12 = 0.000000000001 n nano 10^-9 = 0.000000001 u micro 10^-6 = 0.000001 m milli 10^-3 = 0.001 c centi 10^-2 = 0.01 d deci 10^-1 = 0.1 da deka 10^ 1 = 10 h hecto 10^ 2 = 100 k kilo 10^ 3 = 1000 M mega 10^ 6 = 1000000 G giga 10^ 9 = 1000000000 T tera 10^12 = 1000000000000 P peta 10^15 = 1000000000000000 E exa 10^18 = 1000000000000000000 Z zetta 10^21 = 1000000000000000000000 Y yotta 10^24 = 1000000000000000000000000 The symbol for micro is the Greek letter mu, often written u in an ASCII context where this Greek letter is not available. See also http://physics.nist.gov/cuu/Units/prefixes.html Binary prefixes The binary prefixes resemble the decimal ones, but have an additional 'i' (and "Ki" starts with a capital 'K'). The names are formed by taking the first syllable of the names of the decimal prefix with roughly the same size, followed by "bi" for "binary". Prefix Name Value Ki kibi 2^10 = 1024 Mi mebi 2^20 = 1048576 Gi gibi 2^30 = 1073741824 Ti tebi 2^40 = 1099511627776 Pi pebi 2^50 = 1125899906842624 Ei exbi 2^60 = 1152921504606846976 See also http://physics.nist.gov/cuu/Units/binary.html Discussion Before these binary prefixes were introduced, it was fairly common to use k=1000 and K=1024, just like b=bit, B=byte. Unfortunately, the M is capital already, and cannot be capitalized to indicate binary-ness. At first that didn't matter too much, since memory modules and disks came in sizes that were powers of two, so everyone knew that in such contexts "kilobyte" and "megabyte" meant 1024 and 1048576 bytes, respectively. What originally was a sloppy use of the prefixes "kilo" and "mega" started to become regarded as the "real true meaning" when computers were involved. But then disk technology changed, and disk sizes became arbitrary numbers. After a period of uncertainty all disk manufacturers settled on the standard, namely k=1000, M=1000k, G=1000M. The situation was messy: in the 14k4 modems, k=1000; in the 1.44MB diskettes, M=1024000; etc. In 1998 the IEC approved the standard that defines the binary prefixes given above, enabling people to be precise and unambiguous. Thus, today, MB = 1000000B and MiB = 1048576B. In the free software world programs are slowly being changed to conform. When the Linux kernel boots and says hda: 120064896 sectors (61473 MB) w/2048KiB Cache the MB are megabytes and the KiB are kibibytes.COLOPHON

This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.Linux2001-12-22 UNITS(7)