| Kibibits (Kibit) | Yobioctets (Yio) |
|---|---|
| 1 Kibibit | 1.05879118407 × 10-22 Yio |
| 2 Kibibits | 2.11758236814 × 10-22 Yio |
| 3 Kibibits | 3.1763735522 × 10-22 Yio |
| 4 Kibibits | 4.23516473627 × 10-22 Yio |
| 5 Kibibits | 5.29395592034 × 10-22 Yio |
| 10 Kibibits | 1.05879118407 × 10-21 Yio |
| 20 Kibibits | 2.11758236814 × 10-21 Yio |
| 25 Kibibits | 2.64697796017 × 10-21 Yio |
| 50 Kibibits | 5.29395592034 × 10-21 Yio |
| 100 Kibibits | 1.05879118407 × 10-20 Yio |
| Reference | Kibibits (Kibit) | Yobioctets (Yio) |
|---|---|---|
| A plain text message (160 characters) | 1.25 Kibit | 1.32349 × 10-22 Yio |
| A three-minute MP3 | 23437.5 Kibit | 2.48154 × 10-18 Yio |
| A smartphone photo | 31250 Kibit | 3.30872 × 10-18 Yio |
| A high-definition film | 31250000 Kibit | 3.30872 × 10-15 Yio |
| A dual-layer Blu-ray disc | 390625000 Kibit | 4.1359 × 10-14 Yio |
The kibibit is a unit of digital information equal to 1,024 bits. Its symbol is Kibit. It is the first of the binary prefixes, a set of units defined by the International Electrotechnical Commission in 1998 to end a confusion that had run through computing since the 1960s.
The problem was straightforward. Computers address memory in powers of two, so memory came in chunks of 1,024 rather than 1,000. Engineers borrowed the metric prefix kilo for that quantity because 1,024 is close to 1,000, and for small numbers the approximation was harmless. But storage and transmission counted in true thousands, so the same prefix meant two different things depending on which part of the machine was being described.
The IEC's solution was to coin new names. Kibi is a contraction of kilo binary, and the pattern continues with mebi, gibi, tebi, pebi, exbi, zebi and yobi. Each is 1,024 times the one below, and each symbol takes the form of a capital letter followed by a lowercase i: Ki, Mi, Gi, Ti and so on. The kilobit then means one thousand bits and nothing else.
A kibibit is 128 octets, and the gap from a kilobit is 2.4 per cent. That small difference is why the two were confused for so long: at this scale nobody notices. The error compounds by 2.4 per cent at every step, reaching 5 per cent at the mebibit, 7 per cent at the gibibit and 21 per cent by the yobibit, which is where the ambiguity became genuinely expensive.
Adoption has been partial and uneven. Standards bodies, the Linux kernel and most technical documentation use the IEC prefixes correctly. Consumer software largely does not, and many programs still write KB while dividing by 1,024. The result is that a reader must often infer from context which convention a number follows, which is exactly what the standard was written to prevent.
In practice the kibibit itself appears mainly in the specifications of small memory chips, in serial memory used by embedded systems, and in protocol documents where an exact power of two matters. Anywhere the number 1,024 is meant rather than 1,000, this is the correct unit.
One kibibit equals 1,024 bits, 128 octets, or 1.024 kilobits.
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.