Bits Per Second - Kbps, Mbps, Gbps

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The data rate of a computer network connection is normally measured in units of bits per second (bps). Network equipment makers rate the maximum network bandwidth level their products support using the standard units of Kbps, Mbps and Gbps.

Definitions

One kilobit per second (Kbps) equals 1000 bits per second (bps). Note that Kbps is sometimes also written as “kbps” - both carry the same meaning.  Some also write Kbps as "Kb/sec" or "Kb/s" that also mean the same.

One megabit per second (Mbps) equals 1000 Kbps or one million bps. Mbps, Mb/sec and Mb/s all mean the same.

One gigabit per second (Gbps) equals 1000 Mbps or one million Kbps or one billion bps. Gbps, Gb/sec and Gb/s all mean the same.

Avoiding the Confusion Between Bits and Bytes

For historical reasons, data rates for disk drives and some other (non-network) computer equipment are sometimes shown in bytes per second (Bps with an uppercase 'B) rather than bits per second (bps with a lowercase 'b'). In those cases,

  • one KBps equals one kilobyte per second
  • one MBps equals one megabyte per second, and
  • one GBps equals one gigabyte per second

Because one byte equals eight bits, converting these ratings to the corresponding lowercase 'b' form can be done simply multiplying by 8:

  • one KBps equals 8 Kbps
  • one MBps equals 8 Mbps
  • one GBps equals 8 Gbps

To avoid confusion between bits and bytes, networking professionals always refer to network connection speeds in terms of bps (lowercase 'b') ratings.

Speed Ratings of Common Network Equipment

Network gear with Kbps speed ratings tends to be older and low performance by modern standards. Old dialup modems supported data rates up to 56 Kbps, for example.

Most network equipment features Mbps speed ratings. Examples include;

  • home Internet connections can range from low values like 1 Mbps up to 100 Mbps and even higher in some cases
  • 802.11g Wi-Fi connections rate at 54 Mbps
  • Older Ethernet connections rate at 100 Mbps
  • 802.11n Wi-Fi connections rate at 150 Mbps, 300 Mbps and higher increments

HIgh-end gear features Gbps speed rating.  Examples include:

  • Gigabit Ethernet supports 1 Gbps
  • so-called backbone network links that feed Internet providers and cell towers support multiple Gbps

What Comes After Gbps?

1000 Gbps equals 1 terabit per second (Tbps). Few technologies for Tbps speed networking exist today. The Internet2 project has developed Tbps connections to support its experimental network, and some industry companies have also built testbeds and successfully demonstrate Tbps links. Due to the high cost of the equipment and challenges to operate such a network reliably, expect it will be many more years before these speed levels become practical for general use.

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