| Petabits (Pbit) | Yobibits (Yibit) |
|---|---|
| 1 Petabit | 8.27180612553 × 10-10 Yibit |
| 2 Petabits | 0.00000000165436122511 Yibit |
| 3 Petabits | 0.00000000248154183766 Yibit |
| 4 Petabits | 0.00000000330872245021 Yibit |
| 5 Petabits | 0.00000000413590306277 Yibit |
| 10 Petabits | 0.00000000827180612553 Yibit |
| 20 Petabits | 0.0000000165436122511 Yibit |
| 25 Petabits | 0.0000000206795153138 Yibit |
| 50 Petabits | 0.0000000413590306277 Yibit |
| 100 Petabits | 0.0000000827180612553 Yibit |
| Reference | Petabits (Pbit) | Yobibits (Yibit) |
|---|---|---|
| A plain text message (160 characters) | 1.28 × 10-12 Pbit | 1.05879 × 10-21 Yibit |
| A three-minute MP3 | 0.000000024 Pbit | 1.98523 × 10-17 Yibit |
| A smartphone photo | 0.000000032 Pbit | 2.64698 × 10-17 Yibit |
| A high-definition film | 0.000032 Pbit | 2.64698 × 10-14 Yibit |
| A dual-layer Blu-ray disc | 0.0004 Pbit | 3.30872 × 10-13 Yibit |
The petabit is a unit of digital information equal to a thousand terabits, or a million billion bits. Its symbol is Pbit. It sits at the boundary between quantities that are routinely deployed and quantities that still belong to research laboratories and to totals aggregated across whole networks.
A petabit is 125 teraoctets. That is the storage of roughly a hundred and twenty-five large consumer hard drives, or in more everyday terms about thirty thousand hours of high-definition video — three and a half years of continuous viewing. No single device holds a petabit; the figure describes systems rather than objects.
The most striking use of the unit is in optical transmission records. Research groups in Japan, the Netherlands and elsewhere have carried more than a petabit per second down a single strand of fibre, achieved by combining multi-core fibre — several light-guiding paths inside one cladding — with hundreds of separate wavelengths and advanced modulation. Those results run over tens of kilometres in the laboratory, not the thousands of kilometres a working sea cable must cross.
At the network level the petabit describes aggregate capacity. The total interconnect capacity of a large data centre, the combined capacity of all cables landing on a continent, and the peak throughput of the largest content networks are all quoted in petabits per second. These are sums over many links rather than the rating of any one of them.
Storage systems reach petabit scale too, though they are always labelled in octets. A large scientific archive holding a hundred petaoctets is holding eight hundred petabits, and facilities of that size exist for genomics, particle physics and astronomical survey data. The particle detectors at CERN discard the vast majority of what they see precisely because keeping it would exceed even these capacities.
The prefix peta comes from the Greek for five, because a petabit is a thousand raised to the fifth power in bits. That naming pattern continues upward with exa for six and zetta for seven, so the ladder above the petabit is regular and easy to extend.
One petabit equals 1,000,000,000,000,000 bits, 1,000 terabits, 125 teraoctets, or about 0.8882 pebibits.
The yobibit is a unit of digital information equal to two to the eightieth power bits, which is 1,024 zebibits. Its symbol is Yibit. It is the largest of the binary prefixes defined by the International Electrotechnical Commission, and the binary counterpart of the yottabit.
At this step the two conventions differ by 20.9 per cent. That gap is the culmination of the argument for the binary prefixes: a naming habit that was 2.4 per cent wrong at the kibibit is now a fifth wrong, which no engineering document can tolerate. The IEC series stops here because the decimal series stopped at yotta when it was defined in 1998.
When the metric system gained ronna and quetta in 2022, the binary series was not extended to match. There are no accepted names above yobi, so a quantity of two to the ninetieth bits has no short form and must be written out. This is a gap in the system that will presumably be filled when someone needs it, though at present nothing comes close.
A yobibit is 151,115,727,451,828,646,838,272 octets, or 128 zebioctets. The world's entire stock of data is somewhere in the low hundreds of zettaoctets, which is a fraction of a per cent of a yobioctet. Nothing at this scale has been built, is being built, or is presently planned.
The unit is nevertheless properly defined, and that completeness has a purpose. A measurement system whose rules run out at a certain size forces every future user to invent an extension, and competing extensions are how ambiguity begins. Defining the whole ladder in advance costs nothing and prevents that.
For anyone reading technical documents, the practical lesson of the whole binary series is the lowercase i. Kibit, Mibit, Gibit, Tibit, Pibit, Eibit, Zibit and Yibit are binary; kbit, Mbit, Gbit, Tbit, Pbit, Ebit, Zbit and Ybit are decimal; and the difference between them grows from negligible to a fifth as you climb. A writer who omits the i has left the reader to guess.
One yobibit equals 1,024 zebibits, 151,115,727,451,828,646,838,272 octets, or about 1.209 yottabits.