Data-rate units

Bit rates (data-rate units)
Name	Symbol	Multiple
bit per second	bit/s	1	1
Metric prefixes (SI)
kilobit per second	kbit/s	10³	1000¹
megabit per second	Mbit/s	10⁶	1000²
gigabit per second	Gbit/s	10⁹	1000³
terabit per second	Tbit/s	10¹²	1000⁴
Binary prefixes (IEC 80000-13)
kibibit per second	Kibit/s	2¹⁰	1024¹
mebibit per second	Mibit/s	2²⁰	1024²
gibibit per second	Gibit/s	2³⁰	1024³
tebibit per second	Tibit/s	2⁴⁰	1024⁴

In telecommunications, data transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multiples of bits per second (bit/s) and bytes per second (B/s). For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second (Mbit/s).

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 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.

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 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 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 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
125 megabytes 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
125 gigabytes per second

Decimal multiples of bytes

These units are often not used in the suggested ways; see § Variations.

Kilobyte per second

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

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	⁠1/8⁠ × 10³
kibibit per second	Kibit/s	1,024	128	2¹⁰	2⁷
kilobyte per second	kB/s	8,000	1,000	8 × 10³	10³
kibibyte per second	KiB/s	8,192	1,024	2¹³	2¹⁰
megabit per second	Mbit/s	1,000,000	125,000	10⁶	⁠1/8⁠ × 10⁶
mebibit per second	Mibit/s	1,048,576	131,072	2²⁰	2¹⁷
megabyte per second	MB/s	8,000,000	1,000,000	8 × 10⁶	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	⁠1/8⁠ × 10⁹
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	8 × 10⁹	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	⁠1/8⁠ × 10¹²
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	8 × 10¹²	10¹²
tebibyte per second	TiB/s	8,796,093,022,208	1,099,511,627,776	2⁴³	2⁴⁰

Examples of bit rates

Quantity	Unit	bits per second	bytes per second	Field	Description
56	kbit/s	56,000	7,000	Networking	56 kbit modem – 56,000 bit/s
64	kbit/s	64,000	8,000	Networking	64 kbit/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/s^[1]^[2]^{[dubious – discuss]}
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
1	Gbit/s	1,000,000,000	125,000,000	Networking	1 Gigabit Ethernet
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^[3]
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^[4]
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 3 Gbit/s – Second generation
500	MB/s	4,000,000,000	500,000,000	Computer data interfaces	PCI Express x1 v2.0
5.0	Gbit/s	5,000,000,000	625,000,000	Computer data interfaces	USB 3.0 SuperSpeed - a.k.a. USB 3.1 Gen1
750	MB/s	6,000,000,000	750,000,000	Computer data interfaces	SATA III 6 Gbit/s – Third generation
1,067	MB/s	8,533,333,333	1,066,666,667	Computer data interfaces	PCI-X 64 bit 133 MHz
10	Gbit/s	10,000,000,000	1,250,000,000	Computer data interfaces	USB 3.1 SuperSpeed - a.k.a. USB 3.1 Gen2
1,250	MB/s	10,000,000,000	1,250,000,000	Computer data interfaces	Thunderbolt
2,500	MB/s	20,000,000,000	2,500,000,000	Computer data interfaces	Thunderbolt 2
5,000	MB/s	40,000,000,000	5,000,000,000	Computer data interfaces	Thunderbolt 3
8,000	MB/s	64,000,000,000	8,000,000,000	Computer data interfaces	PCI Express x16 v2.0
12,000	MB/s	96,000,000,000	12,000,000,000	Computer data interfaces	InfiniBand 12X QDR
16,000	MB/s	128,000,000,000	16,000,000,000	Computer data interfaces	PCI Express x16 v3.0

Notes

^ "Penn Researchers Calculate How Much the Eye Tells the Brain". 26 July 2006.
^ Koch, Kristin; McLean, Judith; Segev, Ronen; Freed, Michael A.; Berry, Michael J.; Balasubramanian, Vijay; Sterling, Peter (2006-07-25). "How Much the Eye Tells the Brain". Current Biology. 16 (14): 1428–1434. Bibcode:2006CBio...16.1428K. doi:10.1016/j.cub.2006.05.056. ISSN 0960-9822. PMC 1564115. PMID 16860742.
^ "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. Retrieved 2008-01-31.
^ "Samsung overtakes". 21 November 2007.

References

International Electrotechnical Commission (2007). "Prefixes for binary multiples" (archived). Retrieved on 2007-05-06. - updated page Archived 2020-05-11 at the Wayback Machine 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?" Archived 2016-03-05 at the Wayback Machine

External links

Valid8 Data Rate Calculator

[1] "Penn Researchers Calculate How Much the Eye Tells the Brain". 26 July 2006.

[2] Koch, Kristin; McLean, Judith; Segev, Ronen; Freed, Michael A.; Berry, Michael J.; Balasubramanian, Vijay; Sterling, Peter (2006-07-25). "How Much the Eye Tells the Brain". Current Biology. 16 (14): 1428–1434. Bibcode:2006CBio...16.1428K. doi:10.1016/j.cub.2006.05.056. ISSN 0960-9822. PMC 1564115. PMID 16860742.

[3] "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. Retrieved 2008-01-31.

[4] "Samsung overtakes". 21 November 2007.

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