| Yobioctets (Yio) | Gigabits (Gbit) |
|---|---|
| 1 Yobioctet | 9.67140655692 × 1015 Gbit |
| 2 Yobioctets | 1.93428131138 × 1016 Gbit |
| 3 Yobioctets | 2.90142196708 × 1016 Gbit |
| 4 Yobioctets | 3.86856262277 × 1016 Gbit |
| 5 Yobioctets | 4.83570327846 × 1016 Gbit |
| 10 Yobioctets | 9.67140655692 × 1016 Gbit |
| 20 Yobioctets | 1.93428131138 × 1017 Gbit |
| 25 Yobioctets | 2.41785163923 × 1017 Gbit |
| 50 Yobioctets | 4.83570327846 × 1017 Gbit |
| 100 Yobioctets | 9.67140655692 × 1017 Gbit |
| Reference | Yobioctets (Yio) | Gigabits (Gbit) |
|---|---|---|
| A plain text message (160 characters) | 1.32349 × 10-22 Yio | 0.00000128 Gbit |
| A three-minute MP3 | 2.48154 × 10-18 Yio | 0.024 Gbit |
| A smartphone photo | 3.30872 × 10-18 Yio | 0.032 Gbit |
| A high-definition film | 3.30872 × 10-15 Yio | 32 Gbit |
| A dual-layer Blu-ray disc | 4.1359 × 10-14 Yio | 400 Gbit |
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.
The gigabit is a unit of digital information equal to one thousand million bits, or one billion in the short scale. Its symbol is Gbit. It is the unit that names the current standard of wired networking, and the word gigabit has become shorthand for a particular level of capability rather than merely a quantity.
Gigabit Ethernet, standardised in 1998 and 1999, carries one gigabit per second over ordinary twisted-pair copper cabling up to a hundred metres. It replaced the hundred-megabit standard that preceded it and remains the connection built into most computers, switches and routers. That single decision fixed the meaning of gigabit for a generation of engineers.
In octets, a gigabit is 125 megaoctets. A gigabit-per-second link therefore moves about 125 megaoctets each second in ideal conditions, so a two-gigaoctet film transfers in around sixteen seconds. Real transfers are slower because protocol overhead, disc speed and the far end of the connection all impose their own limits, and it is unusual for storage to keep up with the network at these rates.
Domestic fibre services now advertise gigabit speeds routinely, and in many countries the figure has become a marketing threshold rather than a technical one. Very few households can use it: a gigabit connection is enough to stream around two hundred high-definition video services at once. Its real benefit is not peak speed but headroom, since a link that is never near capacity has consistently low latency.
Memory chips are specified in gigabits for the same reason smaller ones are specified in megabits: the count reflects the number of storage cells on the die. An 8-gigabit chip holds one gigaoctet, and eight such chips make an 8-gigaoctet memory module. Flash memory follows the same convention, so a 512-gigabit flash die holds 64 gigaoctets.
Above the gigabit the scale continues in thousands. Ten-gigabit Ethernet is standard in data centres, forty and hundred-gigabit links join buildings and cities, and the backbone of the internet runs at multiples of these. Each step keeps the same relationship to the octet, and each step is quoted in bits per second because that is what the optics and the copper actually carry.
One gigabit equals 1,000,000,000 bits, 1,000 megabits, 125 megaoctets, or about 0.9313 gibibits.