| Gibioctets (Gio) | Exabits (Ebit) |
|---|---|
| 1 Gibioctet | 0.000000008589934592 Ebit |
| 2 Gibioctets | 0.000000017179869184 Ebit |
| 3 Gibioctets | 0.000000025769803776 Ebit |
| 4 Gibioctets | 0.000000034359738368 Ebit |
| 5 Gibioctets | 0.00000004294967296 Ebit |
| 10 Gibioctets | 0.00000008589934592 Ebit |
| 20 Gibioctets | 0.00000017179869184 Ebit |
| 25 Gibioctets | 0.0000002147483648 Ebit |
| 50 Gibioctets | 0.0000004294967296 Ebit |
| 100 Gibioctets | 0.0000008589934592 Ebit |
| Reference | Gibioctets (Gio) | Exabits (Ebit) |
|---|---|---|
| A plain text message (160 characters) | 0.000000149012 Gio | 1.28 × 10-15 Ebit |
| A three-minute MP3 | 0.00279397 Gio | 2.4 × 10-11 Ebit |
| A smartphone photo | 0.00372529 Gio | 3.2 × 10-11 Ebit |
| A high-definition film | 3.72529 Gio | 0.000000032 Ebit |
| A dual-layer Blu-ray disc | 46.5661 Gio | 0.0000004 Ebit |
The gibioctet is a unit of digital information equal to 1,073,741,824 octets, which is 1,024 mebioctets. Its symbol is Gio. It is the binary counterpart of the gigaoctet, and the 7.4 per cent difference between them is the single most common cause of confusion about data units.
This is the unit in which computer memory is actually sold, whatever the packaging says. A module labelled 8 GB holds 8 gibioctets, which is 8.59 gigaoctets. It could not hold anything else: memory addressing is binary, and a module with a decimal capacity would leave part of its address range unpopulated. The label is a convenient shorthand rather than a measurement.
Storage, by contrast, is genuinely decimal. A drive sold as 500 gigaoctets holds five hundred thousand million octets, and the operating system divides that by 1,024 three times and reports 465.7 gibioctets. The two figures describe the same hardware. Neither party is being dishonest; they are simply counting in different bases, and the labelling convention differs by industry.
Cloud computing has made the distinction visible in contracts. Virtual machine sizes, container memory limits and the parameters that control how much memory a program may use are all specified in gibioctets, because they map onto real memory pages. A limit of 4 GB set in a decimal-minded tool and 4 GiB set in a binary one differ by nearly three hundred megaoctets, which is enough to change whether a program runs.
For everyday scale, a gibioctet holds about a thousand books as plain text, a few hundred photographs, or twenty minutes of high-definition video. It is roughly what a modern web browser occupies in memory with a dozen pages open, which is a fair illustration of how the standard for what counts as a small amount has moved.
The correct symbol is Gio, and it appears in system tools, in virtualisation documentation and in standards. Where a document writes GB for memory, the safe reading is gibioctets; where it writes GB for a disc or a network, the safe reading is gigaoctets. The habit of checking which is meant costs a second and prevents a seven per cent error.
One gibioctet equals 1,073,741,824 octets, 1,024 mebioctets, 8 gibibits, or about 1.074 gigaoctets.
The exabit is a unit of digital information equal to a thousand petabits, or a billion billion bits. Its symbol is Ebit. At this scale no device, no cable and no building is being described. The exabit measures the traffic of whole regions and the output of entire industries over stretches of time.
An exabit is 125 petaoctets. The most common place to meet the unit is in figures for global internet traffic, which are usually given in exaoctets per month. Worldwide traffic passed one exaoctet per month around 2004, reached about a hundred by 2017 and is now several hundred, which in bits is several thousand exabits every month.
Those totals divide in revealing ways. The overwhelming majority is video, and the rest is dominated by software updates, cloud synchronisation and machine-to-machine traffic rather than by anything a person is actively reading. A single popular film released simultaneously worldwide can move a measurable fraction of an exabit in a day.
Storage at this scale exists only as aggregates. The combined capacity of all the hard drives and flash memory manufactured in a year is measured in hundreds of exaoctets, which is thousands of exabits. Estimates of all the data held by humanity at any moment run into the tens of zettaoctets, and the exabit is the unit one step below that in which the components of such estimates are counted.
Scientific instruments produce exabit quantities before any of it is stored. The Square Kilometre Array radio telescope generates raw data at a rate that would fill exaoctets within days, and its design is built around discarding and summarising in real time rather than recording. The same is true of the large particle detectors and of high-resolution climate simulations.
The prefix exa comes from the Greek for six, the exabit being a thousand to the sixth power in bits. It was adopted in 1975 along with peta, at a time when no one expected either to describe anything but astronomical or theoretical quantities. Both are now ordinary units in the technology industry, which says something about how fast the numbers grew.
One exabit equals 1,000 petabits, 125 petaoctets, or about 0.8674 exbibits.