In telecommunications, data rate units are commonly multiples of bits per second and bytes per second . For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second . They are used as units of measurement for expressing data transfer rate, the average number of bits (bit rate), characters or symbols (symbol rate), or data blocks per unit time passing through a communication link in a data-transmission system.
Standards for unit symbols and prefixes
Unit symbol The ISQ symbols for the bit and byte are bit and B, respectively. In the context of data-rate units, one byte consists of 8 bits, and is synonymous with the unit octet. The abbreviation bps is often used to mean , so that when a connection is advertised, it usually means that the maximum achievable bandwidth is (one million bits per second), which is (megabyte per second), or about (mebibyte per second). The Institute of Electrical and Electronics Engineers (IEEE) uses the symbol b for bit.
Unit prefixes In both the SI and ISQ, the prefix k stands for kilo, meaning 1000, while Ki is the symbol for the binary prefix kibi-, meaning 1024. The binary prefixes were introduced in 1998 by the International Electrotechnical Commission (IEC) and in IEEE 1541-2002 which was reaffirmed on 27 March 2008. The letter K is often used as a non-standard abbreviation for 1,024, especially in "KB" to mean KiB, the kilobyte in its binary sense. In the context of data rates, however, typically only decimal prefixes are used, and they have their standard SI interpretation.
Variations In 1999, the IEC published Amendment 2 to "IEC 60027-2: Letter symbols to be used in electrical technology – Part 2: Telecommunications and electronics". This standard, approved in 1998, introduced the prefixes kibi-, mebi-, gibi-, tebi-, pebi-, and exbi- to be used in specifying binary multiples of a quantity. The name is derived from the first two letters of the original SI prefixes followed by bi (short for binary). It also clarifies that the SI prefixes are used only to mean powers of 10 and never powers of 2.
Decimal multiples of bits These units are often used in a manner inconsistent with the IEC standard.
Kilobit per second Kilobit per second (symbol or , often abbreviated "kbps") is a unit of data transfer rate equal to: 1,000 bits per second 125 bytes per second
Megabit per second Megabit per second (symbol or , often abbreviated "Mbps") is a unit of data transfer rate equal to: 1,000 kilobits per second 1,000,000 bits per second 125,000 bytes per second 125 kilobytes per second
Gigabit per second Gigabit per second (symbol or , often abbreviated "Gbps") is a unit of data transfer rate equal to: 1,000 megabits per second 1,000,000 kilobits per second 1,000,000,000 bits per second 125,000,000 bytes per second 125 megabytes per second
Terabit per second Terabit per second (symbol or , sometimes abbreviated "Tbps") is a unit of data transfer rate equal to: 1,000 gigabits per second 1,000,000 megabits per second 1,000,000,000 kilobits per second 1,000,000,000,000 bits per second 125,000,000,000 bytes per second 125 gigabytes per second
Petabit per second Petabit per second (symbol or , sometimes abbreviated "Pbps") is a unit of data transfer rate equal to: 1,000 terabits per second 1,000,000 gigabits per second 1,000,000,000 megabits per second 1,000,000,000,000 kilobits per second 1,000,000,000,000,000 bits per second 125,000,000,000,000 bytes per second 125 terabytes per second
Decimal multiples of bytes These units are often not used in the suggested ways; see .
Kilobyte per second kilobyte per second (sometimes abbreviated "kBps") is a unit of data transfer rate equal to: 8,000 bits per second 1,000 bytes per second 8 kilobits per second
Megabyte per second megabyte per second (can be abbreviated as MBps) is a unit of data transfer rate equal to: 8,000,000 bits per second 1,000,000 bytes per second 1,000 kilobytes per second 8 megabits per second
Gigabyte per second gigabyte per second (can be abbreviated as GBps) is a unit of data transfer rate equal to: 8,000,000,000 bits per second 1,000,000,000 bytes per second 1,000,000 kilobytes per second 1,000 megabytes per second 8 gigabits per second
Terabyte per second terabyte per second (can be abbreviated as TBps) is a unit of data transfer rate equal to: 8,000,000,000,000 bits per second 1,000,000,000,000 bytes per second 1,000,000,000 kilobytes per second 1,000,000 megabytes per second 1,000 gigabytes per second 8 terabits per second
Conversion table NameSymbolbit per secondbyte per secondbit per second(formula)byte per second(formula)bit per secondbit/s10.1251byte per secondB/s8181kilobit per secondkbit/s1,000125103 × 103kibibit per secondKibit/s1,02412821027kilobyte per secondkB/s8,0001,0008 × 103103kibibyte per secondKiB/s8,1921,024213210megabit per secondMbit/s1,000,000125,000106 × 106mebibit per secondMibit/s1,048,576131,072220217megabyte per secondMB/s8,000,0001,000,0008 × 106106mebibyte per secondMiB/s8,388,6081,048,576223220gigabit per secondGbit/s1,000,000,000125,000,000109 × 109gibibit per secondGibit/s1,073,741,824134,217,728230227gigabyte per secondGB/s8,000,000,0001,000,000,0008 × 109109gibibyte per secondGiB/s8,589,934,5921,073,741,824233230terabit per secondTbit/s1,000,000,000,000125,000,000,0001012 × 1012tebibit per secondTibit/s1,099,511,627,776137,438,953,472240237terabyte per secondTB/s8,000,000,000,0001,000,000,000,0008 × 10121012tebibyte per secondTiB/s8,796,093,022,2081,099,511,627,776243240
Examples of bit rates
QuantityUnitbits per secondbytes per secondFieldDescription56kbit/s56,0007,000Networking56 kbit modem – 64kbit/s64,0008,000Networking64 kbit/s in an ISDN B channel or best quality, uncompressed telephone line.1,536kbit/s1,536,000192,000Networking24 channels of telephone in the US, or a good VTC T1.10Mbit/s10,000,0001,250,000Networking107 bit/s is the speed of classic Ethernet: 10BASE2, 10BASE5, 10BASE-T10Mbit/s10,000,0001,250,000BiologyResearch suggests that the human retina transmits data to the brain at the rate of ca. 107 bit/s54Mbit/s54,000,0006,750,000Networking802.11g, Wireless G LAN100Mbit/s100,000,00012,500,000NetworkingFast Ethernet600Mbit/s600,000,00075,000,000Networking802.11n, Wireless N LAN1Gbit/s1,000,000,000125,000,000Networking1 Gigabit Ethernet10Gbit/s10,000,000,0001,250,000,000Networking10 Gigabit Ethernet100Gbit/s100,000,000,00012,500,000,000Networking100 Gigabit Ethernet1Tbit/s1,000,000,000,000125,000,000,000NetworkingSEA-ME-WE 4 submarine communications cable – 1.28 terabits per second4kbit/s4,000500Audio dataminimum achieved for encoding recognizable speech (using special-purpose speech codecs)8kbit/s8,0001,000Audio datalow bit rate telephone quality32kbit/s32,0004,000Audio dataMW quality and ADPCM voice in telephony, doubling the capacity of a 30 chan link to 60 ch.128kbit/s128,00016,000Audio data128 kbit/s MP3 – 192kbit/s192,00024,000Audio data192 kbit/s MP3 – 1,411.2kbit/s1,411,200176,400Audio dataCD audio (uncompressed, 16 bit samples × 44.1 kHz × 2 channels)2Mbit/s2,000,000250,000Video data30 channels of telephone audio or a Video Tele-Conference at VHS quality8Mbit/s8,000,0001,000,000Video dataDVD quality27Mbit/s27,000,0003,375,000Video dataHDTV quality1.244Gbit/s1,244,000,000155,500,000NetworkingOC-24, a SONET data channel9.953Gbit/s9,953,000,0001,244,125,000NetworkingOC-192, a SONET data channel39.813Gbit/s39,813,000,0004,976,625,000NetworkingOC-768, a SONET data channel, the fastest in current use60MB/s480,000,00060,000,000Computer data interfacesUSB 2.0 High-Speed98.3MB/s786,432,00098,304,000Computer data interfacesFireWire IEEE 1394b-2002 S800120MB/s960,000,000120,000,000Computer data interfacesHarddrive read, Samsung SpinPoint F1 HD103Uj133MB/s1,064,000,000133,000,000Computer data interfacesParallel ATA UDMA 6133MB/s1,064,000,000133,000,000Computer data interfacesPCI 32-bit at 33 MHz (standard configuration)188MB/s1,504,000,000188,000,000Computer data interfacesSATA I – First generation375MB/s3,000,000,000375,000,000Computer data interfacesSATA II – Second generation500MB/s4,000,000,000500,000,000Computer data interfacesPCI Express x1 v2.05.0Gbit/s5,000,000,000625,000,000Computer data interfacesUSB 5Gbps750MB/s6,000,000,000750,000,000Computer data interfacesSATA III – Third generation1,067MB/s8,533,333,3331,066,666,667Computer data interfacesPCI-X 64 bit 133 MHz10Gbit/s10,000,000,0001,250,000,000Computer data interfacesUSB 10Gbps1,250MB/s10,000,000,0001,250,000,000Computer data interfacesThunderbolt2,500MB/s20,000,000,0002,500,000,000Computer data interfacesThunderbolt 25,000MB/s40,000,000,0005,000,000,000Computer data interfacesThunderbolt 38,000MB/s64,000,000,0008,000,000,000Computer data interfacesPCI Express x16 v2.012,000MB/s96,000,000,00012,000,000,000Computer data interfacesInfiniBand 12X QDR16,000MB/s128,000,000,00016,000,000,000Computer data interfacesPCI Express x16 v3.0
See also Binary prefix Bit rate List of interface bit rates Orders of magnitude (bit rate) Orders of magnitude (data) Metric prefix Instructions per second
Notes
References International Electrotechnical Commission (2007). "Prefixes for binary multiples" (archived). Retrieved on 2007-05-06. - updated page lacks table but now references IEC 80000-13:2008 rather than IEC 60027-2. IEC 60027-2 "Letter symbols to be used in electrical technology – Part 2: Telecommunications and electronics+ Donald Knuth: "What is a kilobyte?"
External links Valid8 Data Rate Calculator