| Yobibits (Yibit) | Mebioctets (Mio) |
|---|---|
| 1 Yobibit | 1.44115188076 × 1017 Mio |
| 2 Yobibits | 2.88230376152 × 1017 Mio |
| 3 Yobibits | 4.32345564228 × 1017 Mio |
| 4 Yobibits | 5.76460752303 × 1017 Mio |
| 5 Yobibits | 7.20575940379 × 1017 Mio |
| 10 Yobibits | 1.44115188076 × 1018 Mio |
| 20 Yobibits | 2.88230376152 × 1018 Mio |
| 25 Yobibits | 3.6028797019 × 1018 Mio |
| 50 Yobibits | 7.20575940379 × 1018 Mio |
| 100 Yobibits | 1.44115188076 × 1019 Mio |
| Reference | Yobibits (Yibit) | Mebioctets (Mio) |
|---|---|---|
| A plain text message (160 characters) | 1.05879 × 10-21 Yibit | 0.000152588 Mio |
| A three-minute MP3 | 1.98523 × 10-17 Yibit | 2.86102 Mio |
| A smartphone photo | 2.64698 × 10-17 Yibit | 3.8147 Mio |
| A high-definition film | 2.64698 × 10-14 Yibit | 3814.7 Mio |
| A dual-layer Blu-ray disc | 3.30872 × 10-13 Yibit | 47683.7 Mio |
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 mebioctet is a unit of digital information equal to 1,048,576 octets, which is 1,024 kibioctets. Its symbol is Mio. It is the binary counterpart of the megaoctet, and the two differ by 4.9 per cent — the point at which a careful writer starts distinguishing them.
The unit's most visible home is the processor cache. The fast memory built into a processor to hold recently used data is sized in binary, and modern chips carry caches measured in mebioctets: a few hundred kibioctets at the second level and tens of mebioctets at the third. Those figures are exact powers of two because the cache is addressed by dividing an address into fixed bit fields.
Block sizes and buffers follow the same logic. Filesystems allocate in blocks, database engines read in pages, compression tools work in windows, and all of these are powers of two, most often a few mebioctets. A tool that offers a buffer of 16 megaoctets almost always means 16 mebioctets, because the underlying allocation is a shift rather than a multiplication.
The distinction has become visible to ordinary users through the discrepancy between what a download claims and what a file manager reports. A file described as 100 megaoctets on a website is often 100 mebioctets on disc, or the reverse, and the resulting 4.9 per cent difference is enough to make a progress bar look wrong without anything actually being wrong.
For scale, a mebioctet holds a million characters of unaccented text — roughly a long novel, or five hundred pages. It is also a single photograph from a modest camera, or eight seconds of high-definition video. The same unit therefore describes both a very large amount of text and a very small amount of video, which says a good deal about the relative cost of representing the two.
The IEC notation Mio is used in technical documentation, in the Linux kernel, in filesystem tools and in standards. It remains rare in consumer software, where MB is written for both quantities. When a figure matters, the safest habit is to compute in octets and convert once at the end.
One mebioctet equals 1,048,576 octets, 1,024 kibioctets, 8 mebibits, or about 1.049 megaoctets.