| Data rate unitsIn telecommunications, bit rate or data transfer rate is the average number of bits, characters, or blocks per unit time passing between equipment in a data transmission system. This is typically measured in multiples of the unit bit per second or byte per second. Various other units may also be used to measure the data rate. Bit rates |
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Decimal prefixes (SI) |
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Name | Symbol | Multiple |
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kilobit per second | kbit/s | 103 | megabit per second | Mbit/s | 106 | gigabit per second | Gbit/s | 109 | terabit per second | Tbit/s | 1012 | Binary prefixes (IEC 60027-2) |
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kibibit per second | Kibit/s | 210 | mebibit per second | Mibit/s | 220 | gibibit per second | Gibit/s | 230 | tebibit per second | Tibit/s | 240 |
Standards for prefixes and suffixesSee also: Bit rate for the differences between gross bitrate and net bitrate and between throughput and goodput. To be as explicit as possible, both the prefix and the suffix of the unit must be known. For example, the abbreviation 2 Mb can actually be expanded in 4 different ways (mega- vs mebi- and -bit vs -byte). The difference in the associated numbers can be significant: Unit | Bits | Bits / 1,000,000 |
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Mega-bit | 1,000,000 | 1.0 | Mebi-bit | 1,048,576 | 1.05 | Mega-byte | 8,000,000 | 8.0 | Mebi-byte | 8,388,608 | 8.39 |
The table above shows an approximate 5% difference between the corresponding mega- and mebi- units with a 800% difference between -bit and -byte units. Explicitness in units is important because difference can become even larger across different prefix units. Prefix: k vs Kik- stands for kilo, meaning 1,000, while Ki- stands for kilobinary ("kibi-"), meaning 1,024. The standardized binary prefixes such as Ki- were relatively recently introduced (in IEEE 1541-2002 that was reaffirmed on 27 March 2008). K- is often used to mean 1,024, especially in KB, the kilobyte. Suffix: b vs Bb stands for bit and B stands for byte. In the context of data rate units, one byte refers to 8 bits. For example, when a 1 Mb/s connection is advertised, it usually means that the maximum achievable download bandwidth is 1 megabit/s (million bits per second), which is actually 0.125 MB/s (megabyte per second), or about 0.1192 MiB/s (mebibyte per second). Problematic variationsIn 1999, the International Electrotechnical Commission (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 be used only to mean powers of 10 and never powers of 2. Decimal multiples of bitsThese units are often not used in the proper way. See section above, "Problematic variations". Kilobit per secondA kilobit per second (Kbit/s or Kb/s) is a unit of data transfer rate equal to: - 1,000 bits per second or
- 125 bytes per second.
Megabit per secondA megabit per second (Mbit/s or Mb/s; not to be confused with mbit/s which means millibit per second, or with Mbitps which means megabit picosecond) is a unit of data transfer rate equal to: - 1,000,000 bits per second or
- 1,000 kilobits per second or
- 125,000 bytes per second or
- 125 kilobytes per second.
Gigabit per secondA gigabit per second (Gbit/s, or Gb/s) is a unit of data transfer rate equal to: - 1,000 megabits per second or
- 1,000,000 kilobits per second or
- 1,000,000,000 bits per second or
- 125,000,000 bytes per second.
Terabit per secondA tera per second (Tbit/s, or Tb/s) is a unit of data transfer rate equal to: - 1,000 gigabits per second or
- 1,000,000 megabits per second or
- 1,000,000,000 kilobits per second or
- 1,000,000,000,000 bits per second or
- 125,000,000,000 bytes per second.
Binary multiples of bitsFor more details on prefixes such as kibi-, mebi-, gibi-, and tebi-, see Binary prefix. Note that for binary prefixes the prefix name (e.g. "kibi") is not capitalized, but the prefix symbol (eg "Ki") is. Kibibit per secondA kibibit per second (Kibit/s or Kib/s) is a unit of data transfer rate equal to: Mebibit per secondA mebibit per second (Mibit/s or Mib/s) is a unit of data transfer rate equal to: - 1,048,576 bits per second or
- 1,024 kibibits per second.
Gibibit per secondA gibibit per second (Gibit/s or Gib/s) is a unit of data transfer rate equal to: - 1,073,741,824 bits per second or
- 1,048,576 kibibits per second or
- 1,024 mebibits per second.
Tebibit per secondA tebibit per second (Tibit/s or Tib/s) is a unit of data transfer rate equal to: - 1,099,511,627,776 bits per second or
- 1,073,741,824 kibibits per second.
- 1,048,576 mebibits per second or
- 1,024 gibibits per second.
Decimal multiples of bytesWARNING: These units are often not used in the suggested ways! See section above, "Problematic variations". Kilobyte per secondA kilobyte per second (kB/s) is a unit of data transfer rate equal to: - 8,000 bits per second, or
- 1,000 bytes per second, or
- 8 kilobits per second.
Megabyte per second(not to be confused with Mb/s – Mega bits per second) A megabyte per second (MB/s) is a unit of data transfer rate equal to: - 8,000,000 bits per second, or
- 1,000,000 bytes per second, or
- 1,000 kilobytes per second, or
- 8 megabits per second.
Gigabyte per secondA gigabyte per second (GB/s) is a unit of data transfer rate equal to: - 8,000,000,000 bits per second, or
- 1,000,000,000 bytes per second, or
- 1,000,000 kilobytes per second, or
- 1,000 megabytes per second, or
- 8 gigabits per second.
Terabyte per secondA terabyte per second (TB/s) is a unit of data transfer rate equal to: - 8,000,000,000,000 bits per second, or
- 1,000,000,000,000 bytes per second, or
- 1,000,000,000 kilobytes per second, or
- 1,000,000 megabytes per second, or
- 1,000 gigabytes per second, or
- 8 terabits per second.
Binary multiples of bytesFor more details on prefixes such as kibi-, mebi-, gibi-, and tebi-, see Binary prefix. Kibibyte per secondA kibibyte per second (KiB/s) is a unit of data transfer rate equal to: - 1,024 bytes per second, or
- 8 kibibits per second, or
- 8192 bits per second.
Mebibyte per secondA mebibyte per second (MiB/s) is a unit of data transfer rate equal to: - 1,048,576 bytes per second, or
- 1,024 kibibytes per second, or
- 8 mebibits per second, or
- 8192 kibibits per second, or
- 8,388,608 bits per second.
Gibibyte per secondA gibibyte per second (GiB/s) is a unit of data transfer rate equal to: - 1,073,741,824 bytes per second, or
- 1,048,576 kibibytes per second, or
- 1,024 mebibytes per second, or
- 8 gibibits per second, or
- 8192 mebibits per second, or
- 8,388,608 kibibits per second, or
- 8,589,934,592 bits per second.
Tebibyte per secondA tebibyte per second (TiB/s) is a unit of data transfer rate equal to: - 1,099,511,627,776 bytes per second, or
- 1,073,741,824 kibibytes per second, or
- 1,048,576 mebibytes per second, or
- 1,024 gibibytes per second, or
- 8 tebibits per second, or
- 8192 gibibits per second, or
- 8,388,608 mebibits per second, or
- 8,589,934,592 kibibits per second, or
- 8,796,093,022,208 bits per second.
Conversion formula|
bit per second | bit/s | 1 | 0.125 | 1 | 1/8 | byte per second | B/s | 8 | 1 | 8 | 1 | kilobit per second | kbit/s | 1,000 | 125 | 103 | 103/8 | kibibit per second | Kibit/s | 1,024 | 128 | 210 | 27 | kilobyte per second | kB/s | 8,000 | 1,000 | 8x103 | 103 | kibibyte per second | KiB/s | 8,192 | 1,024 | 213 | 210 | megabit per second | Mbit/s | 1,000,000 | 125,000 | 106 | 106/8 | mebibit per second | Mibit/s | 1,048,576 | 131,072 | 220 | 217 | megabyte per second | MB/s | 8,000,000 | 1,000,000 | 8x106 | 106 | mebibyte per second | MiB/s | 8,388,608 | 1,048,576 | 223 | 220 | gigabit per second | Gbit/s | 1,000,000,000 | 125,000,000 | 109 | 109/8 | gibibit per second | Gibit/s | 1,073,741,957 | 134,217,728 | 230 | 227 | gigabyte per second | GB/s | 8,000,000,000 | 1,000,000,000 | 8x109 | 109 | gibibyte per second | GiB/s | 8,589,934,592 | 1,073,741,824 | 233 | 230 | terabit per second | Tbit/s | 1,000,000,000,000 | 125,000,000,000 | 1012 | 1012/8 | tebibit per second | Tibit/s | 1,099,511,627,776 | 137,438,953,472 | 240 | 237 | terabyte per second | TB/s | 8,000,000,000,000 | 1,000,000,000,000 | 8x1012 | 1012 | tebibyte per second | TiB/s | 8,796,093,022,208 | 1,099,511,627,776 | 243 | 240 |
Examples of bit ratesMain article: List of device bit rates |
56 | kbit/s | 56,000 | 7,000 | Networking | 56kbit modem – 56 kbit/s – 56,000 bit/s | 64 | kbit/s | 64,000 | 8,000 | Networking | 64kbit/s in an ISDN B channel or best quality, uncompressed telephone line. | 1,536 | kbit/s | 1,536,000 | 192,000 | Networking | 24 channels of telephone in the US, or a good VTC T1. | 1 | Gbit/s | 1,000,000,000 | 125,000,000 | Networking | Gigabit Ethernet | 10 | Gbit/s | 10,000,000,000 | 1,250,000,000 | Networking | 10 Gigabit Ethernet | 1 | Tbit/s | 1,000,000,000,000 | 125,000,000,000 | Networking | SEA-ME-WE 4 submarine communications cable – 1.28 terabits per second [1] | 4 | kbit/s | 4,000 | 500 | Audio data | minimum achieved for encoding recognizable speech (using special-purpose speech codecs) | 8 | kbit/s | 8,000 | 1,000 | Audio data | low bit rate telephone quality | 32 | kbit/s | 32,000 | 4,000 | Audio data | MW quality and ADPCM voice in telephony, doubling the capacity of a 30 chan link to 60 ch. | 128 | kbit/s | 128,000 | 16,000 | Audio data | 128 kbit/s MP3 – 128,000 bit/s | 192 | kbit/s | 192,000 | 24,000 | Audio data | Nearly CD quality[citation needed] for a file compressed in the MP3 format | 1,411.2 | kbit/s | 1,411,200 | 176,400 | Audio data | CD audio (uncompressed, 16 bit samples �- 44.1 kHz �- 2 channels) | 2 | Mbit/s | 2,000,000 | 250,000 | Video data | 30 channels of telephone audio or a Video Tele-Conference at VHS quality | 8 | Mbit/s | 8,000,000 | 1,000,000 | Video data | DVD quality | 27 | Mbit/s | 27,000,000 | 3,375,000 | Video data | HDTV quality | 1.244 | Gbit/s | 1,244,000,000 | 155,500,000 | Networking | OC-24, a 1.244 Gbit/s SONET data channel | 9.953 | Gbit/s | 9,953,000,000 | 1,244,125,000 | Networking | OC-192, a 9.953 Gbit/s SONET data channel | 39.813 | Gbit/s | 39,813,000,000 | 4,976,625,000 | Networking | OC-768, a 39.813 Gbit/s SONET data channel, the fastest in current use | 60 | MB/s | 480,000,000 | 60,000,000 | Computer data interfaces | USB 2.0 | 625 | MB/s | 5,000,000,000 | 625,000,000 | Computer data interfaces | USB 3.0 | 98.3 | MB/s | 786,432,000 | 98,304,000 | Computer data interfaces | FireWire IEEE 1394b-2002 S800 | 120 | MB/s | 960,000,000 | 120,000,000 | Computer data interfaces | Harddrive read, Samsung SpinPoint F1 HD103Uj [2] | 133 | MB/s | 1,064,000,000 | 133,000,000 | Computer data interfaces | PATA 33 – 133 MB/s | 188 | MB/s | 1,504,000,000 | 188,000,000 | Computer data interfaces | SATA 1.5Gbit/s – First generation | 375 | MB/s | 3,000,000,000 | 375,000,000 | Computer data interfaces | SATA 3Gbit/s – Second generation | 750 | MB/s | 6,000,000,000 | 750,000,000 | Computer data interfaces | SATA 6Gbit/s – Third generation | 533 | MB/s | 4,264,000,000 | 533,000,000 | Computer data interfaces | PCI 133 – 533 MB/s | 1250 | MB/s | 10,000,000,000 | 1,250,000,000 | Computer data interfaces | Thunderbolt | 8000 | MB/s | 64,000,000,000 | 8,000,000,000 | Computer data interfaces | PCI Express x16 v2.0 | 12000 | MB/s | 96,000,000,000 | 12,000,000,000 | Computer data interfaces | InfiniBand 12X QDR |
See also Notes- ^ "Fujitsu Completes Construction of SEA-ME-WE 4 Submarine Cable Network". Fujitsu Press Releases. Fujitsu. 2005-12-13. Archived from the original on 2007-03-17. http://web.archive.org/web/2007031722 3056/http://www.fujitsu.com/global/ne ws/pr/archives/month/2005/20051213-01 .html. Retrieved 2008-01-31.
- ^ "Samsung overtakes". http://www.tomshardware.com/reviews/s amsung-overtakes-a-bang,1730-9.html.
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