| Gigabits per second (Gbit/s) | Zebibits per second (Zibit/s) |
|---|---|
| 1 Gigabit per second | 8.47032947254 × 10-13 Zibit/s |
| 2 Gigabits per second | 1.69406589451 × 10-12 Zibit/s |
| 3 Gigabits per second | 2.54109884176 × 10-12 Zibit/s |
| 4 Gigabits per second | 3.38813178902 × 10-12 Zibit/s |
| 5 Gigabits per second | 4.23516473627 × 10-12 Zibit/s |
| 10 Gigabits per second | 8.47032947254 × 10-12 Zibit/s |
| 20 Gigabits per second | 1.69406589451 × 10-11 Zibit/s |
| 25 Gigabits per second | 2.11758236814 × 10-11 Zibit/s |
| 50 Gigabits per second | 4.23516473627 × 10-11 Zibit/s |
| 100 Gigabits per second | 8.47032947254 × 10-11 Zibit/s |
| Reference | Gigabits per second (Gbit/s) | Zebibits per second (Zibit/s) |
|---|---|---|
| A dial-up modem | 0.000056 Gbit/s | 4.74338 × 10-17 Zibit/s |
| Typical home broadband | 0.1 Gbit/s | 8.47033 × 10-14 Zibit/s |
| Gigabit Ethernet | 1 Gbit/s | 8.47033 × 10-13 Zibit/s |
| Streaming a 4K film | 0.025 Gbit/s | 2.11758 × 10-14 Zibit/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.
The zebibit per second is a unit of data transfer rate equal to two to the seventieth power bits per second, which is 1,024 exbibits per second. Its symbol is Zibit/s. It is the binary counterpart of the zettabit per second, and the two differ by 18.1 per cent — approaching a fifth.
Nothing runs at this rate, and nothing is designed to. A zebibit per second is about a thousand times the total instantaneous traffic of the internet, and it would move the world's entire stock of stored data in a matter of minutes. The unit exists because the IEC series, like the metric series it parallels, was defined completely rather than only as far as anyone then needed.
That completeness is a deliberate design principle rather than an oversight. A measurement system whose names run out at some arbitrary point forces every future user to improvise an extension, and improvised extensions conflict with one another. Defining the whole ladder in advance costs nothing and removes the possibility.
The eighteen per cent gap at this level is the clearest illustration of why the binary series was needed at all. At the kibibit the two conventions differed by 2.4 per cent, which nobody noticed; the discrepancy multiplies by 1.024 at each step, and by here it is large enough that no reader could treat the two labels as interchangeable even in casual writing.
In octets a zebibit per second is 147,573,952,589,676,412,928, or 128 exbioctets per second. Expressing the same rate in every unit on the scale is an exercise rather than an application, but it is one a converter has to perform correctly, because the arithmetic does not become approximate when the quantity becomes unreachable.
The practical lesson is the one the whole binary series teaches: the lowercase i is not optional. It is the only mark in a written figure that distinguishes a power of two from a power of ten, and by this point in the scale the two are nearly a fifth apart.
One zebibit per second equals 1,024 exbibits per second, 147,573,952,589,676,412,928 octets per second, or about 1.181 zettabits per second.