Conversion from Tebibits per second to Gigabits per second

Information about the Tebibit per second (Tibit/s)

The tebibit per second is a unit of data transfer rate equal to 1,099,511,627,776 bits per second, which is 1,024 gibibits per second. Its symbol is Tibit/s. It is the binary counterpart of the terabit per second, and the two differ by 10 per cent.

Ten per cent is the point at which the distinction becomes a matter of money rather than of pedantry. A supplier quoting a system at a hundred terabits per second and a customer measuring a hundred tebibits per second are not describing the same performance, and the difference is ten terabits — more than most organisations' entire external connectivity.

The rate belongs to the interior of very large machines. The aggregate memory bandwidth of a rack of accelerators, or the internal switching capacity of a large network chip, reaches this range, and both are built from power-of-two structures: memory channels of fixed binary width, switch ports in powers of two, buffers sized in binary. Expressing their totals with binary prefixes preserves the arithmetic that produced them.

In octets a tebibit per second is 137,438,953,472, or 128 gibioctets per second. That is more than any single storage device can supply and more than any external cable carries. It is a figure that describes something happening inside a cabinet, between chips connected by short traces on a board, where the physical distance is measured in centimetres.

Optical research also brushes this range. A laboratory demonstration carrying a petabit per second down one fibre is a thousand times higher, but individual wavelength channels and the electronics driving them work at tebibit-scale aggregates, and papers reporting them often state the binary figure because the underlying frame sizes are binary.

The habit of writing the lowercase i is worth keeping even where the reader is unlikely to check. A number written unambiguously can be converted correctly by anyone who reads it later; one written ambiguously cannot be repaired, and at ten per cent the ambiguity is no longer harmless.

One tebibit per second equals 1,024 gibibits per second, 137,438,953,472 octets per second, or about 1.100 terabits per second.

Information about the 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.