| Yobibits per second (Yibit/s) | Terabits per second (Tbit/s) |
|---|---|
| 1 Yobibit per second | 1208925819615 Tbit/s |
| 2 Yobibits per second | 2417851639229 Tbit/s |
| 3 Yobibits per second | 3626777458844 Tbit/s |
| 4 Yobibits per second | 4835703278459 Tbit/s |
| 5 Yobibits per second | 6044629098073 Tbit/s |
| 10 Yobibits per second | 12089258196146 Tbit/s |
| 20 Yobibits per second | 24178516392293 Tbit/s |
| 25 Yobibits per second | 30223145490366 Tbit/s |
| 50 Yobibits per second | 60446290980731 Tbit/s |
| 100 Yobibits per second | 120892581961463 Tbit/s |
| Reference | Yobibits per second (Yibit/s) | Terabits per second (Tbit/s) |
|---|---|---|
| A dial-up modem | 4.63221 × 10-20 Yibit/s | 0.000000056 Tbit/s |
| Typical home broadband | 8.27181 × 10-17 Yibit/s | 0.0001 Tbit/s |
| Gigabit Ethernet | 8.27181 × 10-16 Yibit/s | 0.001 Tbit/s |
| Streaming a 4K film | 2.06795 × 10-17 Yibit/s | 0.000025 Tbit/s |
The yobibit per second is a unit of data transfer rate equal to two to the eightieth power bits per second, which is 1,024 zebibits per second. Its symbol is Yibit/s. It is the largest binary transfer rate the International Electrotechnical Commission has named, and the binary counterpart of the yottabit per second.
At this final step the binary and decimal conventions differ by 20.9 per cent, and that number is the conclusion of the argument the IEC prefixes were created to settle. A naming habit that was 2.4 per cent wrong at the kibibit has grown, through eight successive multiplications by 1.024, into a discrepancy of more than a fifth. No measurement system can carry an ambiguity that large.
The unit describes nothing. Global internet traffic runs at roughly an exabit per second, so a yobibit per second is over a million times the total communication of the human species. No link, no aggregate and no forecast reaches it, and none is expected to.
The binary series stops here because the decimal series stopped at yotta when the IEC standard was written in 1998. When ronna and quetta were added to the metric system in 2022, no matching binary names were defined, so a rate of two to the ninetieth bits per second has no accepted short form. That gap will presumably be filled if it is ever needed, which at present it is not.
Defining a rung of a ladder nobody has climbed still has a purpose. A system whose names run out forces its users to improvise, and improvised extensions conflict; writing the whole series out in advance means the rule, rather than a table of exceptions, is all anyone has to learn. That is the same reasoning that gave the metric system its complete prefix set.
For any reader of technical material the lesson of the whole binary series is a single character. Kibit/s, Mibit/s, Gibit/s, Tibit/s, Pibit/s, Eibit/s, Zibit/s and Yibit/s are binary; kbit/s, Mbit/s, Gbit/s, Tbit/s, Pbit/s, Ebit/s, Zbit/s and Ybit/s are decimal; and the difference between them widens from a rounding error to a fifth as you climb.
One yobibit per second equals 1,024 zebibits per second, 151,115,727,451,828,646,838,272 octets per second, or about 1.209 yottabits per second.
The terabit per second is a unit of data transfer rate equal to a thousand gigabits per second. Its symbol is Tbit/s. It is the unit of the internet's backbone: the submarine cables, the exchange points and the long-haul optical links that carry traffic between continents.
A single modern transoceanic cable carries several hundred terabits per second. It achieves this not with one enormous channel but with wavelength division multiplexing, which sends dozens of separate colours of light down each fibre at once, and with several fibre pairs in the same cable. Each wavelength carries a few hundred gigabits, and the totals add up.
The historical comparison is worth stating plainly. The first transatlantic telephone cable, laid in 1956, carried thirty-six simultaneous voice calls. A cable laid in the 2020s carries hundreds of terabits per second, enough for hundreds of millions of simultaneous calls. That is a factor of roughly ten million in seventy years, and it was achieved almost entirely by changing what is sent down the glass rather than by laying more cable.
Internet exchange points, where networks meet and hand traffic to one another, publish their throughput in terabits per second. The largest in Europe and Asia peak in the tens of terabits, and those public graphs are among the most reliable measurements of how heavily the internet is being used at a given moment, because they count real traffic rather than capacity.
In octets, a terabit per second is 125 gigaoctets per second — the contents of a large laptop's disc moved every second, continuously. No single storage system can feed such a link; the traffic on these routes is the aggregate of millions of separate connections, each of them tiny by comparison.
Laboratory records go far higher, into petabits per second, using multi-core fibre and hundreds of wavelengths at once, though over short distances under controlled conditions. The gap between what is demonstrated in a laboratory and what is deployed under an ocean has historically been about a decade.
One terabit per second equals 1,000 gigabits per second, 125 gigaoctets per second, or about 0.9095 tebibits per second.