| Zettaoctets (Zo) | Yobioctets (Yio) |
|---|---|
| 1 Zettaoctet | 0.000827180612553 Yio |
| 2 Zettaoctets | 0.00165436122511 Yio |
| 3 Zettaoctets | 0.00248154183766 Yio |
| 4 Zettaoctets | 0.00330872245021 Yio |
| 5 Zettaoctets | 0.00413590306277 Yio |
| 10 Zettaoctets | 0.00827180612553 Yio |
| 20 Zettaoctets | 0.0165436122511 Yio |
| 25 Zettaoctets | 0.0206795153138 Yio |
| 50 Zettaoctets | 0.0413590306277 Yio |
| 100 Zettaoctets | 0.0827180612553 Yio |
| Reference | Zettaoctets (Zo) | Yobioctets (Yio) |
|---|---|---|
| A plain text message (160 characters) | 1.6 × 10-19 Zo | 1.32349 × 10-22 Yio |
| A three-minute MP3 | 3 × 10-15 Zo | 2.48154 × 10-18 Yio |
| A smartphone photo | 4 × 10-15 Zo | 3.30872 × 10-18 Yio |
| A high-definition film | 4 × 10-12 Zo | 3.30872 × 10-15 Yio |
| A dual-layer Blu-ray disc | 5 × 10-11 Zo | 4.1359 × 10-14 Yio |
The zettaoctet is a unit of digital information equal to a thousand exaoctets, or a sextillion octets. Its symbol is Zo. It is the unit in which the total quantity of data in the world is now described, and the only data unit that has given its name to an era.
That name came from the phrase the zettabyte era, used from around 2016, when annual global internet traffic first exceeded one zettaoctet. Estimates of the global datasphere — every file stored anywhere, plus everything created and immediately discarded — passed a hundred zettaoctets a few years later and continue to rise by tens of zettaoctets a year.
Understanding what these figures include matters more than the numbers themselves. They count copies. A single photograph on a phone is also on the phone's backup, on two servers in a cloud provider's data centre, in a caching layer, and possibly in a machine learning training set. Counting stored octets rather than distinct works inflates the total by a large factor that nobody has ever measured precisely.
The composition of the total is dominated by things nobody looks at. Surveillance and security video, most of it overwritten within weeks, is the single largest category. Sensor and telemetry data from industrial equipment, vehicles and buildings is second. Human-authored material of any kind is a minority, and text is a rounding error within that minority.
Manufacturing sets a hard limit on the total. All the world's storage factories together produce a few hundred exaoctets of new capacity per year, which is a fraction of a zettaoctet, so most data created is never stored at all. It is processed as it arrives and thrown away, and this is a deliberate design choice rather than a failure.
For a sense of the scale, a zettaoctet would be about eight thousand million large consumer hard drives, or roughly one for every person on Earth. Stacked flat, that many drives would form a column reaching well beyond the Moon. The unit describes a quantity that only exists as a sum across a whole planet's industry.
One zettaoctet equals 1,000 exaoctets, 1,000,000,000,000 gigaoctets, 8 zettabits, or about 0.8470 zebioctets.
The yobioctet is a unit of digital information equal to two to the eightieth power octets, which is 1,024 zebioctets. Its symbol is Yio. It is the largest binary unit the International Electrotechnical Commission has named, and the binary counterpart of the yottaoctet.
At this final step the binary and decimal conventions differ by 20.9 per cent. That is the end of the argument the IEC prefixes were created to settle: a difference that began as a harmless 2.4 per cent at the kibioctet has grown, by eight successive multiplications of 1.024, into a discrepancy of more than a fifth. No system of measurement can carry an ambiguity that large.
A yobioctet is 1,208,925,819,614,629,174,706,176 octets. The entire quantity of data held by humanity is a few hundred zettaoctets, which is a fraction of a per cent of this. Nothing of this size has been built, and current manufacturing rates would need to continue for many centuries to accumulate one.
The binary series stops at yobi 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 quantity of two to the ninetieth octets has no accepted short form. That gap will presumably be filled if it is ever needed.
The value of defining the top of a ladder nobody has climbed is the same as the value of defining the bottom. A measurement system whose names run out forces its users to improvise, and improvised extensions conflict. Both the metric and the IEC series were written out in full so that the rule, rather than a table of exceptions, is all anyone has to learn.
For any reader of technical material, the lesson of the whole series is one character. Kio, Mio, Gio, Tio, Pio, Eio, Zio and Yio are binary; ko, Mo, Go, To, Po, Eo, Zo and Yo are decimal; and the difference between them widens from a rounding error to a fifth as you climb. That lowercase i is the only thing in a document that says which was meant.
One yobioctet equals 1,024 zebioctets, 1,208,925,819,614,629,174,706,176 octets, 8 yobibits, or about 1.209 yottaoctets.