| Zettabits per second (Zbit/s) | Exaoctets per second (Eo/s) |
|---|---|
| 1 Zettabit per second | 125 Eo/s |
| 2 Zettabits per second | 250 Eo/s |
| 3 Zettabits per second | 375 Eo/s |
| 4 Zettabits per second | 500 Eo/s |
| 5 Zettabits per second | 625 Eo/s |
| 10 Zettabits per second | 1250 Eo/s |
| 20 Zettabits per second | 2500 Eo/s |
| 25 Zettabits per second | 3125 Eo/s |
| 50 Zettabits per second | 6250 Eo/s |
| 100 Zettabits per second | 12500 Eo/s |
| Reference | Zettabits per second (Zbit/s) | Exaoctets per second (Eo/s) |
|---|---|---|
| A dial-up modem | 5.6 × 10-17 Zbit/s | 7 × 10-15 Eo/s |
| Typical home broadband | 1 × 10-13 Zbit/s | 1.25 × 10-11 Eo/s |
| Gigabit Ethernet | 1 × 10-12 Zbit/s | 1.25 × 10-10 Eo/s |
| Streaming a 4K film | 2.5 × 10-14 Zbit/s | 3.125 × 10-12 Eo/s |
The zettabit per second is a unit of data transfer rate equal to a thousand exabits per second. Its symbol is Zbit/s. No system on Earth moves data at this rate, and none is planned; the unit exists because the metric system defines every prefix for every unit, whether or not the combination has yet been needed.
To see how far off it is, take the whole internet. Global traffic at present runs at roughly one exabit per second on average, so the entire planet's communications would have to grow a thousandfold to reach one zettabit per second. At the growth rates of the last two decades that would take somewhere between twenty and thirty years, which is precisely the sort of extrapolation that has been wrong in both directions before.
A zettabit per second is 125 exaoctets per second. Since global data storage manufacturing runs at a few hundred exaoctets a year, a link at this rate would transfer the world's entire annual production of new storage capacity in a couple of seconds. Nothing could be stored at the far end; the data would have to be processed and discarded as it arrived.
That last point is not as fanciful as it sounds. Several existing systems already discard almost everything they receive: particle detectors, radio telescope arrays and network monitoring systems all process far more than they keep, because keeping it is impossible and unnecessary. A zettabit-per-second link would be an extreme case of an architecture that already exists.
The physical obstacles are less absolute than they might appear. The theoretical capacity of a single optical fibre is far above what is used today, and the practical limits come from amplifier noise, non-linear effects and the electronics at each end rather than from the glass itself. Aggregating enough fibres would reach a zettabit per second; the difficulty is that nobody has a reason to.
For a converter, the unit matters because forecasts and capacity models are written in whatever unit keeps the numbers legible. A projection that reaches into the 2050s may reasonably state totals in zettabits per second, and a reader needs to be able to convert that into something familiar.
One zettabit per second equals 1,000 exabits per second, 125 exaoctets per second, or about 0.8470 zebibits per second.
The exaoctet per second is a unit of data transfer rate equal to a thousand petaoctets per second, or eight exabits per second. Its symbol is Eo/s. Nothing built runs at this rate: it is about eight times the total traffic of the entire internet, counted across every network on the planet at once.
The unit is useful mainly for thought experiments about limits. If every hard drive and flash chip manufactured in a year were read simultaneously at full speed, the combined rate would be in this range. So would the total output of every camera sensor in every phone on Earth if they all recorded at once. These are sums over the whole world's hardware, not rates any system experiences.
There is one situation in which very large data volumes really do move faster than any network, and it puts the unit in perspective. Physically shipping a container of hard drives across an ocean transfers more data per second, averaged over the journey, than any cable. A shipping container holding a few exaoctets crossing the Atlantic in a week works out to several gigaoctets per second, and a truck of drives driven across a city beats almost any local link.
That calculation is not a joke; cloud providers offer it as a service. When a customer needs to move petaoctets into a data centre, the provider ships a lorry full of storage rather than attempting the transfer over a network, because the network would take months. The bandwidth of a vehicle is enormous, though its latency is measured in days.
For the unit itself, an exaoctet per second is 125 petaoctets per second, and it would transfer the world's entire stock of stored data — a few hundred zettaoctets — in about a week of continuous running. No mechanism exists to feed such a link, and none is being designed.
A converter must nevertheless handle the unit, because it appears in aggregate capacity models, in academic papers on the theoretical limits of communication, and in any table that lists the metric prefixes completely. A quantity does not need a use for its name to be well formed.
One exaoctet per second equals 1,000 petaoctets per second, 8 exabits per second, or about 0.8674 exbioctets per second.