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In telecommunications, data transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or blocks per unit time passing between equipment in a data transmission system. Most commonly, measurements of data transfer rate are reported in multiples of unit bits per second (bit/s) or occasionally in bytes per second (B/s). The data rates of modern residential high-speed Internet connections are most commonly expressed in multiples of bits per second, such as megabits per second (Mbit/s) or kilobits per second (kbit/s).

Standards for unit symbols and prefixes

See also: Bit rate for the differences between gross bitrate and net bitrate and between throughput and goodput.

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 bit/s, so that when a 1 Mbps connection is advertised, it usually means that the maximum achievable bandwidth is 1 Mbit/s (one million bits per second), which is 0.125 MB/s (megabyte per second), or about 0.1192 MiB/s (mebibyte per second). The Institute of Electrical and Electronics Engineers (IEEE) uses the symbol b for bit.

Prefix

In both the SI and ISQ, the prefix k stands for kilo, meaning 1,000, while Ki is the symbol for the binary prefix kibi-, meaning 1,024. 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.

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 be 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. See above section titled "variations".

Kilobit per second

kilobit per second (symbol kbit/s or kb/s, 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 Mbit/s or Mb/s, often abbreviated "Mbps") is a unit of data transfer rate equal to:

  • 1,000,000 bits per second
  • 1,000 kilobits per second
  • 125,000 bytes per second
  • 125 kilobytes per second

Gigabit per second

gigabit per second (symbol Gbit/s or Gb/s, 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

Terabit per second

terabit per second (symbol Tbit/s or Tb/s, 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

Binary multiples of bits

For more details on prefixes such as kibi, mebi, gibi, tebi, see Binary prefix.

The prefix name for binary prefixes (e.g., "kibi") is not capitalized, but the prefix symbol (e.g. "Ki") is.

Kibibit per second

The kibibit per second (Kibit/s) is a unit of data transfer rate equal to:

  • 1,024 bits per second

Mebibit per second

The mebibit per second (Mibit/s) is a unit of data transfer rate equal to:

  • 1,048,576 bits per second
  • 1,024 kibibits per second

Gibibit per second

The gibibit per second (Gibit/s) is a unit of data transfer rate equal to:

  • 1,073,741,824 bits per second
  • 1,048,576 kibibits per second
  • 1,024 mebibits per second

Tebibit per second

The tebibit per second (Tibit/s) is a unit of data transfer rate equal to:

  • 1,099,511,627,776 bits per second
  • 1,073,741,824 kibibits per second
  • 1,048,576 mebibits per second
  • 1,024 gibibits per second

Decimal multiples of bytes

These units are often not used in the suggested ways! See above section titled "variations".

Kilobyte per second

kilobyte per second (kB/s) 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 (MB/s) 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 (GB/s) 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 (TB/s) 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

Binary multiples of bytes

For more details on prefixes such as kibi-, mebi-, gibi-, and tebi-, see Binary prefix.

Kibibyte per second

The kibibyte per second (KiB/s) is a unit of data transfer rate equal to:

  • 1,024 bytes per second
  • 8 kibibits per second
  • 8192 bits per second

Mebibyte per second

The mebibyte per second (MiB/s) is a unit of data transfer rate equal to:

  • 1,048,576 bytes per second
  • 1,024 kibibytes per second
  • 8 mebibits per second
  • 8192 kibibits per second
  • 8,388,608 bits per second

Gibibyte per second

The gibibyte per second (GiB/s) is a unit of data transfer rate equal to:

  • 1,073,741,824 bytes per second
  • 1,048,576 kibibytes per second
  • 1,024 mebibytes per second
  • 8 gibibits per second
  • 8192 mebibits per second
  • 8,388,608 kibibits per second
  • 8,589,934,592 bits per second

Tebibyte per second

The tebibyte per second (TiB/s) is a unit of data transfer rate equal to:

  • 1,099,511,627,776 bytes per second
  • 1,073,741,824 kibibytes per second
  • 1,048,576 mebibytes per second
  • 1,024 gibibytes per second
  • 8 tebibits per second
  • 8192 gibibits per second
  • 8,388,608 mebibits per second
  • 8,589,934,592 kibibits per second
  • 8,796,093,022,208 bits per second

Conversion table

Name Symbol bit per second byte per second bit per second (formula) byte per second (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 1,073,741,824 134,217,728 230 227
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 rates

Main article: List of device bit rates

Quantity Unit bits per second bytes per second Field Description
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.
10 Mbit/s 10,000,000 1,250,000 Networking 107 bit/s is the speed of classic Ethernet: 10BASE2, 10BASE5, 10BASE-T
10 Mbit/s 10,000,000 1,250,000 Biology Research suggests that the human retina transmits data to the brain at the rate of ca. 107 bit/sec
54 Mbit/s 54,000,000 6,750,000 Networking 802.11g, Wireless G LAN
100 Mbit/s 100,000,000 12,500,000 Networking Fast Ethernet
600 Mbit/s 600,000,000 75,000,000 Networking 802.11n, Wireless N LAN
10 Gbit/s 10,000,000,000 1,250,000,000 Networking 10 Gigabit Ethernet
100 Gbit/s 100,000,000,000 12,500,000,000 Networking 100 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
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 192 kbit/s MP3 – 192,000 bit/s
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 High-Speed
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
133 MB/s 1,064,000,000 133,000,000 Computer data interfaces Parallel ATA UDMA 6
133 MB/s 1,064,000,000 133,000,000 Computer data interfaces PCI 32-bit at 33 MHz (standard configuration)
188 MB/s 1,504,000,000 188,000,000 Computer data interfaces SATA I 1.5 Gbit/s – First generation
375 MB/s 3,000,000,000 375,000,000 Computer data interfaces SATA II 3Gbit/s – Second generation
500 MB/s 4,000,000,000 500,000,000 Computer data interfaces PCI Express x1 v2.0
625 MB/s 5,000,000,000 625,000,000 Computer data interfaces USB 3.0 SuperSpeed
750 MB/s 6,000,000,000 750,000,000 Computer data interfaces SATA III 6 Gbit/s – Third generation
1067 MB/s 8,533,333,333 1,066,666,667 Computer data interfaces PCI-X 64 bit 133 MHz
1250 MB/s 10,000,000,000 1,250,000,000 Computer data interfaces Thunderbolt
2500 MB/s 20,000,000,000 2,500,000,000 Computer data interfaces Thunderbolt 2
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
16000 MB/s 128,000,000,000 16,000,000,000 Computer data interfaces PCI Express x16 v3.0

Source: Wikipedia

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