Data-rate units
In telecommunications, data rate units are commonly multiples of bits per second and bytes per second. For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second.
They are used as units of measurement for expressing data transfer rate, the average number of bits, characters or symbols, or data blocks per unit time passing through a communication link in a data-transmission system.
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, so that when a connection is advertised, it usually means that the maximum achievable bandwidth is , which is , or about . The Institute of Electrical and Electronics Engineers 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 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. 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 is a unit of data transfer rate equal to:- 1,000 bits per second
- 125 bytes per second
Megabit per second
- 1,000 kilobits per second
- 1,000,000 bits per second
- 125,000 bytes per second
- 125 kilobytes per second
Gigabit per second
- 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
- 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
Petabit per second
- 1,000 terabits per second
- 1,000,000 gigabits per second
- 1,000,000,000 megabits per second
- 1,000,000,000,000 kilobits per second
- 1,000,000,000,000,000 bits per second
- 125,000,000,000,000 bytes per second
- 125 terabytes per second
Decimal multiples of bytes
Kilobyte per second
kilobyte per second 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
- 8,000,000 bits per second
- 1,000,000 bytes per second
- 1,000 kilobytes per second
- 8 megabits per second
Gigabyte per second
- 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
- 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
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 – |
| 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 |
| 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 |
| 4 | kbit/s | 4,000 | 500 | Audio data | minimum achieved for encoding recognizable speech |
| 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 – |
| 192 | kbit/s | 192,000 | 24,000 | Audio data | 192 kbit/s MP3 – |
| 1,411.2 | kbit/s | 1,411,200 | 176,400 | Audio data | CD audio |
| 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 SONET data channel |
| 9.953 | Gbit/s | 9,953,000,000 | 1,244,125,000 | Networking | OC-192, a SONET data channel |
| 39.813 | Gbit/s | 39,813,000,000 | 4,976,625,000 | Networking | OC-768, a 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 |
| 188 | MB/s | 1,504,000,000 | 188,000,000 | Computer data interfaces | SATA I – First generation |
| 375 | MB/s | 3,000,000,000 | 375,000,000 | Computer data interfaces | SATA II – 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 – 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 |