| Yobibits (Yibit) | Gigaoctets (Go) |
|---|---|
| 1 Yobibit | 151115727451829 Go |
| 2 Yobibits | 302231454903657 Go |
| 3 Yobibits | 453347182355486 Go |
| 4 Yobibits | 604462909807315 Go |
| 5 Yobibits | 755578637259143 Go |
| 10 Yobibits | 1.51115727452 × 1015 Go |
| 20 Yobibits | 3.02231454904 × 1015 Go |
| 25 Yobibits | 3.7778931863 × 1015 Go |
| 50 Yobibits | 7.55578637259 × 1015 Go |
| 100 Yobibits | 1.51115727452 × 1016 Go |
| Reference | Yobibits (Yibit) | Gigaoctets (Go) |
|---|---|---|
| A plain text message (160 characters) | 1.05879 × 10-21 Yibit | 0.00000016 Go |
| A three-minute MP3 | 1.98523 × 10-17 Yibit | 0.003 Go |
| A smartphone photo | 2.64698 × 10-17 Yibit | 0.004 Go |
| A high-definition film | 2.64698 × 10-14 Yibit | 4 Go |
| A dual-layer Blu-ray disc | 3.30872 × 10-13 Yibit | 50 Go |
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 gigaoctet is a unit of digital information equal to one thousand million octets, or eight gigabits. Its symbol is Go. It is the unit in which most things people actually buy are sized: the memory in a computer, the storage in a phone, the monthly allowance on a mobile contract.
The reference points are familiar. A DVD holds 4.7 gigaoctets and a dual-layer disc 8.5. A Blu-ray holds 25 or 50. A feature film in high definition is 4 to 15 gigaoctets depending on compression, and in ultra-high definition 40 or more. A phone with 128 gigaoctets of storage holds roughly thirty thousand photographs, or a few hundred hours of music.
Memory sizes now sit in this range and are stated in gibioctets even when written as gigaoctets. A module labelled 8 GB holds 8 gibioctets, which is 8.59 gigaoctets, because memory addressing is binary and always has been. The same is true of processor caches and of the page tables that map memory, so anything on the memory side of a computer is binary while anything on the storage side is decimal.
That split is the source of the most familiar consumer complaint about units. A hard drive sold as one teraoctet holds a million million octets, which the operating system divides by 1,024 three times and reports as 931 gigaoctets. Nothing has been lost; the drive holds exactly what the box says, but the two are counting in different bases. Lawsuits over this were settled in the manufacturers' favour, since the decimal usage matches the metric system.
Mobile data allowances made the gigaoctet a household figure. A few gigaoctets a month was generous around 2012 and is now minimal, because video dominates: an hour of standard-definition streaming is about 0.7 gigaoctets, an hour in high definition around 3, and an hour in ultra-high definition 7 or more.
For scale in text, a gigaoctet holds around a thousand full-length books as plain text, or the complete works of most authors many times over. Digital storage stopped being a constraint on text decades ago, and every capacity discussion since has really been about images, sound and video.
One gigaoctet equals 1,000,000,000 octets, 1,000 megaoctets, 8 gigabits, or about 0.9313 gibioctets.