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).
|bit per second||bit/s||1||1|
|Decimal 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|
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.
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. In the context of data rates, however, typically only decimal prefixes are used, and they have their standard SI interpretation.
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.
These units are often used in a manner inconsistent with the IEC standard.
kilobit per second (symbol kbit/s or kb/s, often abbreviated "kbps") is a unit of data transfer rate equal to:
megabit per second (symbol Mbit/s or Mb/s, often abbreviated "Mbps") is a unit of data transfer rate equal to:
gigabit per second (symbol Gbit/s or Gb/s, often abbreviated "Gbps") is a unit of data transfer rate equal to:
terabit per second (symbol Tbit/s or Tb/s, sometimes abbreviated "Tbps") is a unit of data transfer rate equal to:
These units are often not used in the suggested ways; see above section titled "variations".
kilobyte per second (kB/s) is a unit of data transfer rate equal to:
megabyte per second (MB/s) is a unit of data transfer rate equal to:
gigabyte per second (GB/s) is a unit of data transfer rate equal to:
terabyte per second (TB/s) is a unit of data transfer rate equal to:
|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/|
|byte per second||B/s||8||1||8||1|
|kilobit per second||kbit/s||1,000||125||103||1/ × 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/ × 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/ × 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/ × 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|
|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||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 |
|54||Mbit/s||54,000,000||6,750,000||Networking||802.11g, Wireless G LAN|
|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|
|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|
|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|
|1067||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|
|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|
|5000||MB/s||40,000,000,000||5,000,000,000||Computer data interfaces||Thunderbolt 3|
|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|
In telecommunications and computing, bit rate (bitrate or as a variable R) is the number of bits that are conveyed or processed per unit of time.The bit rate is quantified using the bits per second unit (symbol: "bit/s"), often in conjunction with an SI prefix such as "kilo" (1 kbit/s = 1,000 bit/s), "mega" (1 Mbit/s = 1,000 kbit/s), "giga" (1 Gbit/s = 1,000 Mbit/s) or "tera" (1 Tbit/s = 1000 Gbit/s). The non-standard abbreviation "bps" is often used to replace the standard symbol "bit/s", so that, for example, "1 Mbps" is used to mean one million bits per second.
In most environments, one byte per second (1 B/s) corresponds to 8 bit/s.CD and DVD writing speed
Original CD-ROM drives could read data at 150 kibibytes (150 × 210 bytes) per second. As faster drives were released, the write speeds and read speeds for optical discs were multiplied by manufacturers, far exceeding the drive speeds originally released onto the market. In order to market increasing drive speeds, manufacturers used the symbol nX, whereby n is the multiple of the original speed. For example, writing to a CD at 8X will be twice as fast as writing onto a disc at 4X.Internet access
Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Various technologies, at a wide range of speeds have been used by Internet service providers (ISPs) to provide this service.
Internet access was once rare, but has grown rapidly. In 1995, only 0.04 percent of the world's population had access, with well over half of those living in the United States, and consumer use was through dial-up. By the first decade of the 21st century, many consumers in developed nations used faster broadband technology, and by 2014, 41 percent of the world's population had access, broadband was almost ubiquitous worldwide, and global average connection speeds exceeded 1 Mbit/s.Kilobit
The kilobit is a multiple of the unit bit for digital information or computer storage. The prefix kilo- (symbol k) is defined in the International System of Units (SI) as a multiplier of 103 (1 thousand), and therefore,
1 kilobit = 103bits = 1000 bits.The kilobit has the unit symbol kbit or kb.
Using the common byte size of 8 bits, 1 kbit is equal to 125 bytes.
The kilobit is commonly used in the expression of data rates of digital communication circuits as kilobits per second (kbit/s or kb/s), or abbreviated as kbps, as in, for example, a 56 kbps PSTN circuit, or a 512 kbit/s broadband Internet connection.
The unit symbol kb (lowercase 'b') is typographically similar to the international standard unit symbol for the kilobyte, i.e. kB (upper case 'B'). The International Electrotechnical Commission (IEC) recommends the symbol bit instead of b. The prefix kilo- is often used in fields of computer science and information technology with a meaning of multiplication by 1024 instead of 1000, contrary to international standards, in conjunction with the base unit byte and bit, in which case it is to be written as Ki-, with a capital letter K, e.g., 1 Kibit = 1024 bits. The decimal SI definition, 1 kbit/s = 1000 bit/s, is used uniformly in the context of telecommunication transmission speeds.
The kilobit is closely related to the much less used kibibit, a unit multiple derived from the binary prefix kibi- (symbol Ki) of the same order of magnitude, which is equal to 210bits = 1024 bits, or approximately 2% larger than the kilobit. Despite the definitions of these new prefixes, meant for binary-based quantities of storage by international standards organizations, memory semiconductor chips are still marketed using the metric prefix names to designate binary multiples.Orders of magnitude (bit rate)
An order of magnitude is generally a factor of ten. A quantity growing by four orders of magnitude implies it has grown by a factor of 10000 or 104. However, because computers are binary, orders of magnitude are sometimes given as powers of two.
This article presents a list of multiples, sorted by orders of magnitude, for bit rates measured in bits per second. Since some bit rates may measured in other quantities of data or time (like MB/s), information to assist with converting to and from these formats is provided. This article assumes the following:
A group of 8 bits (8 b) constitutes one byte (1 B). The byte is the most common unit of measurement of information (megabyte, mebibyte, gigabyte, gibibyte, etc.).
The decimal SI prefixes kilo, mega etc., are powers of 10. The power of two equivalents are the binary prefixes kibi, mebi, etc.Accordingly:
1 kB (kilobyte) = 1000 bytes = 8000 bits
1 KiB (kibibyte) = 210 bytes = 1024 bytes = 8192 bits
1 kb (kilobit) = 125 bytes = 1000 bits
1 Kib (kibibit) = 210 bits = 1024 bits = 128 bytesOrders of magnitude (data)
An order of magnitude is a factor of ten. A quantity growing by four orders of magnitude implies it has grown by a factor of 10,000 or 104.
This article presents a list of multiples, sorted by orders of magnitude, for digital information storage measured in bits.
The byte is a common unit of measurement of information (kilobyte, kibibyte, megabyte, mebibyte, gigabyte, gibibyte, terabyte, tebibyte, etc.); for the purpose of this article, a byte is a group of 8 bits (octet), a nibble is a group of four bits. Historically, both assumptions have not always been true.
The decimal SI prefixes kilo, mega, giga, tera, etc., are powers of 103 = 1000. The binary prefixes kibi, mebi, gibi, tebi, etc. respectively refer to the corresponding power of 210 = 1024. In casual usage, when 1024 is a close enough approximation of 1000, the two corresponding prefixes are equivalent.
Note: this page mixes between two kinds of entropies:
Entropy (information theory), such as the amount of information that can be stored in DNA
Entropy (thermodynamics), such as entropy increase of 1 mole of waterThese two definitions are not entirely equivalent, see Entropy in thermodynamics and information theory.
For comparison, the Avogadro constant is 6.02214179(3)×1023 entities per mole, based upon the number of atoms in 12 grams of carbon-12 isotope.
In 2012, some hard disks used ~984,573 atoms to store each bit. In January 2012, IBM researchers announced they compressed 1 bit in 12 atoms using antiferromagnetism and a scanning tunneling microscope with iron and copper atoms. This could mean a practical jump from a 1 TB disk to a 100 TB disk.Transfer (computing)
In computer technology, transfers per second and its more common secondary terms gigatransfers per second (abbreviated as GT/s) and megatransfers per second (MT/s) are informal language that refer to the number of operations transferring data that occur in each second in some given data-transfer channel. It is also known as sample rate, i.e. the number of data samples captured per second, each sample normally occurring at the clock edge. The terms are neutral with respect to the method of physically accomplishing each such data-transfer operation; nevertheless, they are most commonly used in the context of transmission of digital data. 1 MT/s is 106 or one million transfers per second; similarly, 1 GT/s means 109, or equivalently in the US/short scale, one billion transfers per second.
The choice of the symbol T for transfer conflicts with the International System of Units, in which T stands for the tesla unit of magnetic flux density. "Megatesla per second" would be a reasonable unit to describe the rate of a rapidly changing magnetic field, such as in a pulsed field magnet or kicker magnet, although the equivalent units of "tesla per microsecond" (T/μs) would reflect typical engineering values better.
These terms alone do not specify the bit rate at which binary data is being transferred, because they do not specify the number of bits transferred in each transfer operation (known as the channel width or word length). In order to calculate the data transmission rate, one must multiply the transfer rate by the information channel width. For example, a data bus eight-bytes wide (64 bits) by definition transfers eight bytes in each transfer operation; at a transfer rate of 1 GT/s, the data rate would be 8 × 109 B/s, i.e. 8 GB/s, or approximately 7.45 GiB/s. The bit rate for this example is 64 Gbit/s (8 × 8 × 109 bit/s).
The formula for a data transfer rate is: Channel width (bits/transfer) × transfers/second = bits/second.
Expanding the width of a channel, for example that between a CPU and a northbridge, increases data throughput without requiring an increase in the channel's operating frequency (measured in transfers per second). This is analogous to increasing throughput by increasing bandwidth but leaving latency unchanged.
The units usually refer to the "effective" number of transfers, or transfers perceived from "outside" of a system or component, as opposed to the internal speed or rate of the clock of the system. One example is a computer bus running at double data rate where data is transferred on both the rising and falling edge of the clock signal. If its internal clock runs at 100 MHz, then the effective rate is 200 MT/s, because there are 100 million rising edges per second and 100 million falling edges per second of a clock signal running at 100 MHz.
SCSI (Small Computer Systems Interface) falls in the megatransfer range of data transfer rate, while newer bus architectures like the front side bus, Quick Path Interconnect, PCI Express and HyperTransport operate at the rate of a few GT/s.