Gigabit per second (Gbit/s)

The gigabit per second is a unit of data transfer rate equal to one thousand million bits per second. Its symbol is Gbit/s, often written Gbps. It names the standard of wired local networking and, increasingly, of domestic fibre connections.

Gigabit Ethernet was standardised in 1998 for optical fibre and in 1999 for ordinary twisted-pair copper, and the copper version is what made it universal. It runs a hundred metres over the same cabling that carried the hundred-megabit standard before it, which meant buildings could be upgraded by replacing equipment rather than wiring. That single property fixed the gigabit as the default connection for a generation.

In octets a gigabit per second is 125 megaoctets per second. That is roughly the speed of a good mechanical hard drive and well below a modern solid-state drive, which is why gigabit networking is no longer the bottleneck it once was: the network can now outrun the storage at one end or the other in many common setups.

Domestic fibre services advertise a gigabit routinely, and the figure has become a marketing threshold more than a technical one. Practically no household can saturate it — a gigabit is enough for around two hundred simultaneous high-definition video streams — and the benefit in daily use is not throughput but the absence of congestion, which keeps latency low and steady.

Above the gigabit the ladder continues in the same steps. Ten-gigabit Ethernet is standard between servers and switches in data centres; twenty-five, forty, hundred and four-hundred-gigabit links join racks, buildings and cities. Each is a multiple of the same unit, and each is still counted in bits per second because that is what the optics and the copper actually carry.

Wireless has followed. The later wireless local network standards quote peak rates above a gigabit per second, though those figures assume a single device, ideal conditions and the full width of the channel. Real wireless throughput in a normal home is typically a third to a half of the advertised peak, and the gap widens with every additional device.

One gigabit per second equals 1,000,000,000 bits per second, 125 megaoctets per second, or about 0.9313 gibibits per second.

Gigabit per second conversion table