Bits Per Second Explained

The Meaning of Bit Rates (Kbps, Mbps & Gbps) and Which Is Fastest

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

These are sometimes called internet speed units because as network speeds increase, it's easier to express them in thousands (kilo-), millions (mega-) or billions (giga-) of units at once.

Definitions

Since kilo- is to mean a value of one thousand, it's used to denote the lowest speed from this group:

  • One kilobit per second (Kbps) equals 1,000 bits per second (bps). This is sometimes written as kbps, Kb/sec or Kb/s but all of them carry the same meaning. 
  • One megabit per second (Mbps) equals 1000 Kbps or one million bps. It's also expressed as Mbps, Mb/sec, and Mb/s.
  • One gigabit per second (Gbps) equals 1000 Mbps, one million Kbps or one billion bps. It's also abbreviated as Gbps, Gb/sec, and Gb/s.

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'). 

  • one Kbps equals one kilobyte per second
  • one MBps equals one megabyte per second
  • 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 dial-up modems supported data rates up to 56 Kbps, for example.

Most network equipment features Mbps speed ratings.

  • Home internet connections can range from low values like 1 Mbps up to 100 Mbps and even higher
  • 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:

  • Gigabit Ethernet supports 1 Gbps
  • 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 operating such a network reliably, expect it will be many more years before these speed levels become practical for general use.

How to Do Data Rate Conversions

It's really simple to convert between these units when you know that there are 8 bits in every byte and that kilo, Mega, and Giga mean thousand, million and billion.

You can do the calculations yourself manually or use any of a number of online calculators.

For example, you can convert Kbps to Mbps with those rules. 15,000 Kbps = 15 Mbps because there are 1,000 kilobits in each 1 megabit.

CheckYourMath is one calculator that supports data rate conversions. You can also use Google, like this.