| Yobibits (Yibit) | Pebibits (Pibit) |
|---|---|
| 1 Yobibit | 1073741824 Pibit |
| 2 Yobibits | 2147483648 Pibit |
| 3 Yobibits | 3221225472 Pibit |
| 4 Yobibits | 4294967296 Pibit |
| 5 Yobibits | 5368709120 Pibit |
| 10 Yobibits | 10737418240 Pibit |
| 20 Yobibits | 21474836480 Pibit |
| 25 Yobibits | 26843545600 Pibit |
| 50 Yobibits | 53687091200 Pibit |
| 100 Yobibits | 107374182400 Pibit |
| Reference | Yobibits (Yibit) | Pebibits (Pibit) |
|---|---|---|
| A plain text message (160 characters) | 1.05879 × 10-21 Yibit | 1.13687 × 10-12 Pibit |
| A three-minute MP3 | 1.98523 × 10-17 Yibit | 0.0000000213163 Pibit |
| A smartphone photo | 2.64698 × 10-17 Yibit | 0.0000000284217 Pibit |
| A high-definition film | 2.64698 × 10-14 Yibit | 0.0000284217 Pibit |
| A dual-layer Blu-ray disc | 3.30872 × 10-13 Yibit | 0.000355271 Pibit |
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.
The pebibit is a unit of digital information equal to 1,125,899,906,842,624 bits, which is 1,024 tebibits or two to the fiftieth power. Its symbol is Pibit. It is the binary counterpart of the petabit, and the gap between them has widened to 12.6 per cent.
That widening is worth watching, because it is the whole argument for the IEC prefixes in one number. Each step up the ladder multiplies the discrepancy by 1.024, so what began as a harmless 2.4 per cent at the kibibit is an eighth of the quantity here and a fifth at the yobibit. A convention that was reasonable for small numbers becomes indefensible for large ones.
A pebibit is 140,737,488,355,328 octets, or 128 tebioctets. Storage of this size exists in supercomputer memory systems, in the fastest scientific data buffers and in the aggregate memory of very large clusters. The largest machines on the list of the world's fastest computers have main memory measured in pebioctets, and the ability to hold an entire simulation in memory rather than on disc is what makes certain calculations feasible at all.
Because these systems are addressed in binary, the binary unit is the correct one and the decimal figure would be an approximation. A cluster with a pebibit of memory does not have a petabit; it has 12.6 per cent more, and a scheduler that allocated on the decimal figure would leave that much unused.
The unit also appears in filesystem limits. Several widely used filesystems have maximum volume or file sizes expressed as exact powers of two, and where those limits fall in this range they are naturally written in pebibytes or pebioctets. Documentation that converts them to decimal units loses the property that made them memorable.
In everyday computing the pebibit is never encountered. It belongs to specifications, to system architecture and to the design of the largest machines, and a converter needs it for exactly those documents. Anywhere the underlying quantity is a power of two, this is the unit that says so without rounding.
One pebibit equals 1,024 tebibits, 140,737,488,355,328 octets, or about 1.126 petabits.