In 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 units bit per second or byte per second.

Bit rates
Decimal prefixes (SI)
Name	Symbol	Multiple
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)
kibibit per second	Kibit/s	210
mebibit per second	Mibit/s	220
gibibit per second	Gibit/s	230
tebibit per second	Tibit/s	240

Contents 1 Avoiding confusion 1.1 Prefix: k vs. Ki 1.2 Suffix: b vs. B 2 Decimal multiples of bits 2.1 Kilobit per second 2.2 Megabit per second 2.3 Gigabit per second 2.4 Terabit per second 3 Binary multiples of bits 3.1 Kibibit per second 3.2 Mebibit per second 3.3 Gibibit per second 3.4 Tebibit per second 4 Decimal multiples of bytes 4.1 Kilobyte per second 4.2 Megabyte per second 4.3 Gigabyte per second 4.4 Terabyte per second 5 Binary multiples of bytes 5.1 Kibibyte per second 5.2 Mebibyte per second 5.3 Gibibyte per second 5.4 Tebibyte per second 6 Conversion formulas 7 Examples 8 See also 9 Notes 10 References

[edit] Avoiding confusion

See also Bit rate for the differences of gross and net bitrate, 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 immense:

Unit	Bits	Bits / 1,000,000
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 approximately 5% difference between the corresponding mega- and mebi- units with an 800% difference between -bit and -byte units. Explicitness in units is important because different interpretations can mean up to an 840% difference in the amount of data considered within one unit (the difference can become even larger across different prefix units).

[edit] Prefix: k vs. Ki

'k' stands for kilo, meaning 1,000, while 'Ki' stands for kibi, meaning 1,024. The standardized binary prefixes such as kibi were relatively recently introduced and still face low adoption. 'K' and 'k' are often used to mean 1,024, especially in KB, the kilobyte.

[edit] Suffix: b vs. B

'b' stands for 'bit' and 'B' stands for 'byte'. However, it has been suggested that 'bit' should not be abbreviated since the difference between bit and byte can lead to confusion. In the context of data rate units, one byte refers to 8 bits. For example, when a "1 Mbps" 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).

Often it is assumed that there are TEN (10, not 8) bits per byte. Each 8 bits may have about two extra checksum-type bits, making ten bits in actual use. So "256 b/s" will be less than "256 B/s", not the opposite from what we might expect.

[edit] Decimal multiples of bits

[edit] Kilobit per second

A kilobit per second (kbit/s or kb/s or kbps) is a unit of data transfer rate equal to:

• 1,000 bits per second or
• 125 bytes per second.

[edit] Megabit per second

A megabit per second (Mbit/s or Mb/s or Mbps) 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.

[edit] Gigabit per second

A gigabit per second (Gbit/s or Gb/s or Gbps) is a unit of data transfer rate equal to:

• 1,000,000,000 bits per second or
• 1,000,000 kilobits per second or
• 1,000 megabits per second or
• 125,000,000 bytes per second.

[edit] Terabit per second

A terabit per second (Tbit/s or Tb/s or Tbps) is a unit of data transfer rate equal to:

• 1,000,000,000,000 bits per second
• 1,000,000,000 kilobits per second or
• 1,000,000 megabits per second or
• 1,000 gigabits per second or
• 125,000,000,000 bytes per second.

[edit] Binary multiples of bits

[edit] Kibibit per second

A kibibit per second (Kibit/s or Kib/s) is a unit of data transfer rate equal to 1,024 bits per second. The word "kibibit" is not capitalized, but the abbreviation "Kibit" is.

[edit] Mebibit per second

A 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.

[edit] Gibibit per second

A 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.

[edit] Tebibit per second

A 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 or
• 1,048,576 mebibits per second or
• 1,024 gibibits per second.

[edit] Decimal multiples of bytes

[edit] Kilobyte per second

A kilobyte per second (kB/s or kBps) 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.

[edit] Megabyte per second

A megabyte per second (MB/s or MBps) 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.

[edit] Gigabyte per second

A gigabyte per second (GB/s or GBps) 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.

[edit] Terabyte per second

A terabyte per second (TB/s or TBps) 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.

[edit] Binary multiples of bytes

[edit] Kibibyte per second

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

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

[edit] Mebibyte per second

A mebibyte per second (MiB/s or MiBps) 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.

[edit] Gibibyte per second

A gibibyte per second (GiB/s or GiBps) 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.

[edit] Tebibyte per second

A tebibyte per second (TiB/s or TiBps) 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.
• 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.

[edit] Conversion formulas

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	10^3	10^3/8
kibibit per second	Kibit/s	1,024	128	2^10	2^7
kilobyte per second	kB/s	8,000	1,000	8*10^3	10^3
kibibyte per second	KiB/s	8,192	1,024	2^13	2^10
megabit per second	Mbit/s	1,000,000	125,000	10^6	10^6/8
mebibit per second	Mibit/s	1,048,576	131,072	2^20	2^17
megabyte per second	MB/s	8,000,000	1,000,000	8*10^6	10^6
mebibyte per second	MiB/s	8,388,608	1,048,576	2^23	2^20
gigabit per second	Gbit/s	1,000,000,000	125,000,000	10^9	10^9/8
gibibit per second	Gibit/s	1,073,741,824	134,217,728	2^30	2^27
gigabyte per second	GB/s	8,000,000,000	1,000,000,000	8*10^9	10^9
gibibyte per second	GiB/s	8,589,934,592	1,073,741,824	2^33	2^30
terabit per second	Tbit/s	1,000,000,000,000	125,000,000,000	10^12	10^12/8
tebibit per second	Tibit/s	1,099,511,627,776	137,438,953,472	2^40	2^37
terabyte per second	TB/s	8,000,000,000,000	1,000,000,000,000	8*10^12	10^12
tebibyte per second	TiB/s	8,796,093,022,208	1,099,511,627,776	2^43	2^40

[edit] Examples

Quantity	Unit	bits per second	bytes per second	Field	Description
56	kbit/s	56,000	7,000	Networking	56k modem - 56 kb/s - 56,000 b/s
64	kbit/s	64,000	8,000	Networking	64k ISDN - 64 kb/s - 64,000 b/s
1536	kbit/s	1,536,000	192,000	Networking	1536k T1 - 1,536,000 b/s (1.536 Mb/s)
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 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	telephone quality
32	kbit/s	32,000	4,000	Audio data	MW quality
128	kbit/s	128,000	16,000	Audio data	128 kb/s MP3 - 128,000 b/s
192	kbit/s	192,000	24,000	Audio data	Nearly CD quality 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	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 Gb/s SONET data channel
9.953	Gbit/s	9,953,000,000	1,244,125,000	Networking	OC-192, a 9.953 Gb/s SONET data channel
39.813	Gbit/s	39,813,000,000	4,976,625,000	Networking	OC-768, a 39.813 Gb/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 [1]
133	MB/s	1,064,000,000	133,000,000	Computer data interfaces	PATA 33 - 133 MB/s
150	MB/s	1,200,000,000	150,000,000	Computer data interfaces	SATA 1.5Gb/s - First generation
300	MB/s	2,400,000,000	300,000,000	Computer data interfaces	SATA 3Gb/s - Second generation
600	MB/s	4,800,000,000	600,000,000	Computer data interfaces	SATA 6Gb/s - Third generation
533	MB/s	4,264,000,000	533,000,000	Computer data interfaces	PCI 133 - 533 MB/s

[edit] See also

• Binary prefix
• Bit rate
• List of device bandwidths
• Orders of magnitude (data)
• SI prefix

[edit] Notes

1. ^ "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/20070317223056/http://www.fujitsu.com/global/news/pr/archives/month/2005/20051213-01.html. Retrieved 2008-01-31. 

[edit] References

• International Electrotechnical Commission (2007). "Prefixes for binary multiples". Retrieved on 2007-05-06.
• IEC 60027-2 "Letter symbols to be used in electrical technology - Part 2: Telecommunications and electronics+