Network Speed Units

Network speed is the rate at which data is transmitted from one device to another across a network. It is measured in bits per second (bps), so a link carrying 300,000,000 bps is shifting 300 million bits every second.

Decimal prefixes

Network speed units use decimal prefixes, so each step up is a jump of 1000 (not 1024). The letters in front of the bps tell you which step you are on:

To change a larger unit into bits per second, multiply by 1000 once for every prefix step. A 450 Mbps connection is 450 × 1000 × 1000 = 450,000,000 bps, because Mbps sits two steps above bps. Going the other way, divide by 1000 for each step: 7,000,000,000 bps is 7,000,000,000 ÷ 1000 ÷ 1000 ÷ 1000 = 7 Gbps.

Bits and bytes

Mb means megabit and MB means megabyte, and they are not the same unit. One byte holds 8 bits, so a 64 Mbps connection moves 64 ÷ 8 = 8 MB of data each second. The capital letter is the clue: a capital B is always bytes, a lowercase b is always bits.

Comparing speeds

To compare speeds that are written in different units, convert them to the same unit first, usually bits per second. Otherwise the larger-looking number can win by accident.

For example, a college campus link runs at 2 Gbps while a nearby primary school link runs at 250 Mbps. Converting gives 2 × 1000 × 1000 = 2,000,000,000 bps for the campus and 250 × 1000 × 1000 = 250,000,000 bps for the school, so the campus link is 8 times faster — even though 2 looks far smaller than 250.