| Yottabits per second (Ybit/s) | Exbioctets per second (Eio/s) |
|---|---|
| 1 Yottabit per second | 108420.217249 Eio/s |
| 2 Yottabits per second | 216840.434497 Eio/s |
| 3 Yottabits per second | 325260.651746 Eio/s |
| 4 Yottabits per second | 433680.868994 Eio/s |
| 5 Yottabits per second | 542101.086243 Eio/s |
| 10 Yottabits per second | 1084202.17249 Eio/s |
| 20 Yottabits per second | 2168404.34497 Eio/s |
| 25 Yottabits per second | 2710505.43121 Eio/s |
| 50 Yottabits per second | 5421010.86243 Eio/s |
| 100 Yottabits per second | 10842021.7249 Eio/s |
| Reference | Yottabits per second (Ybit/s) | Exbioctets per second (Eio/s) |
|---|---|---|
| A dial-up modem | 5.6 × 10-20 Ybit/s | 6.07153 × 10-15 Eio/s |
| Typical home broadband | 1 × 10-16 Ybit/s | 1.0842 × 10-11 Eio/s |
| Gigabit Ethernet | 1 × 10-15 Ybit/s | 1.0842 × 10-10 Eio/s |
| Streaming a 4K film | 2.5 × 10-17 Ybit/s | 2.71051 × 10-12 Eio/s |
The yottabit per second is a unit of data transfer rate equal to a thousand zettabits per second. Its symbol is Ybit/s. For thirty years it was the largest rate the metric system could name, and it describes a speed that has no application anywhere: not in engineering, not in research, and not in any forecast that anyone takes seriously.
Its distance from reality is easy to state. Global internet traffic averages roughly one exabit per second, so a yottabit per second is about a million times the combined communication of the entire human species. The largest single link ever built runs at a few hundred terabits per second, which is a ten-billionth of this figure.
The unit is nonetheless properly defined, and that completeness is the point. The metric system's rule is that every prefix combines with every unit without exception, so a reader who has never seen Ybit/s can decode it from the prefix alone. A system with gaps would need a table of which combinations are legal, and a table is exactly what a rule-based system exists to avoid.
There is a physical way to think about the number. A yottabit per second is 125 zettaoctets per second, and the total quantity of data humanity has ever stored is a few hundred zettaoctets. A link at this rate would therefore transmit the entire accumulated information of the species in a couple of seconds. No such body of data exists in one place to be sent, and nothing at the far end could receive it.
The prefix yotta was adopted in 1991 alongside zetta, at a conference that also had to consider which letters remained free. It stood at the top of the metric ladder until 2022, when ronna and quetta were added above it, partly because data quantities were beginning to approach the old ceiling. Rates have not followed quantities upward at the same pace.
For a converter, handling the unit is a matter of consistency rather than utility. A tool that converts every metric prefix correctly does not need to decide which of them anyone will use, and a figure written in yottabits per second — however unlikely — converts by the same rule as any other.
One yottabit per second equals 1,000 zettabits per second, 125 zettaoctets per second, or about 0.8272 yobibits per second.
The exbioctet per second is a unit of data transfer rate equal to 1,024 pebioctets per second, or two to the sixtieth power octets per second. Its symbol is Eio/s. It is the binary counterpart of the exaoctet per second, and the two differ by 15.3 per cent.
No machine, network or aggregate reaches this rate. An exbioctet per second is more than eight times the total instantaneous traffic of the entire internet, and it would move the world's whole stock of stored data in a matter of minutes. The unit describes a capacity with no source that could supply it and no destination that could take it in.
Two to the sixtieth is nevertheless a familiar number in computing, because it is the size of the address space a 64-bit machine can reach in octets divided by sixteen. The same power of two turns up in filesystem limits, in memory maps and in the design of every system built on that architecture, so the quantity is well known even though no rate approaches it.
The unit exists because the IEC series was defined completely. Every binary prefix pairs with every unit, exactly as every metric prefix does, so that a reader who has never seen Eio/s can decode it from the prefix alone. A system with gaps would need a table of permitted combinations, which is precisely what a rule-based system exists to avoid.
The difference from the decimal unit is worth restating at each level because it compounds. At the kibioctet it was 2.4 per cent, here it is more than an eighth, and at the yobioctet it will be more than a fifth. That growth is the reason the binary prefixes were created, and it is why the lowercase i has to be written even in figures nobody will check.
For a converter, the treatment is mechanical: six multiplications by 1,024 from octets, or the equivalent divisions coming down. The value of doing it correctly is not that anyone will use the result, but that a tool which handles every case the same way can be trusted on the cases that matter.
One exbioctet per second equals 1,024 pebioctets per second, 1,152,921,504,606,846,976 octets per second, or about 1.153 exaoctets per second.