kilobit - megabit - gigabit

Network cables
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Definition: In computer networking, a kilobit normally represents 1000 bits of data. A megabit represents 1000 kilobits and a gigabit represents 1000 megabits (equal to one million kilobits).

Network Data Rates - Bits Per Second

Kilobits, megabits and gigabits traveling over a computer network are typically measured per second.:

  • 1 kilobit per second equals 1 Kbps or kbps (these are equivalent)
  • 1 megabit per second equals 1 Mbps
  • 1 gigabit per second equals 1 Gbps

Slow network connections are measured in kilobits, faster links in megabits, and very fast connections in gigabits.

Examples of Kilobits, Megabits and Gigabits

The table below summarizes common usage of these terms in computer networking. Speed ratings represent the rated maximum of the technology.

standard dial-up modems56 Kbps
typical encoding rates of MP3 music files128 Kbps, 160 Kbps, 256 Kbps, 320 Mbps
maximum encoding rate of Dolby Digital (audio)640 Kbps
T1 line1544 Kbps
traditional Ethernet 10 Mbps
802.11b Wi-Fi11 Mbps
802.11a and 802.11g Wi-Fi54 Mbps
Fast Ethernet100 Mbps
typical 802.11n Wi-FI data rates150 Mbps, 300 Mbps, 450 Mbps, 600 Mbps
typical 802.11ac Wi-Fi data rates433 Mbps, 867 Mbps, 1300 Mbps, 2600 Mbps
Gigabit Ethernet1 Gbps
10 Gigabit Ethernet10 Gbps

The speed ratings of Internet services vary greatly depending on the kind of Internet access technology and also choice of subscription plans.

Many years ago, mainstream broadband connections were rated 384 Kbps and 512 Kbps. Now, speeds above 5 Mbps are common, with 10 Mbps and higher the norm in some cities and countries.

The Problem with Bit Rates

The Mbps and Gbps ratings of network equipment (including Internet connections) gets prominent billing in product sales and marketing.

Unfortunately, these data rates are only indirectly connected to network speed and the performance levels that users of a network actually need.

For example, consumers and home networks normally generate only small amount of network traffic, but in rapid bursts, from usages like Web browsing and email. Even a relatively modest sustained data rate like 5 Mbps is sufficient for most Netflix streaming. Network load only gradually increases as more devices and users are added. Much of that traffic is incoming from the Internet rather than self-generate within the home, where long-distance networking delays and other limits of a household's Internet link often (not always) dictate the overall performance experience.

See also - How Network Performance is Measured

The Confusion Between Bits and Bytes

Many people less familiar with computer networking believe one kilobit equals 1024 bits. This is untrue in networking but may be valid in other contexts. Specifications for network adapters, network routers and other equipment always use 1000-bit kilobits as the basis of their quoted data rates. The confusion arises as computer memory and disk drive manufacturers often use 1024-byte kilobytes as the basis of their quoted capacities.

See also - What is the Difference Between Bits and Bytes?