| Tebioctets (Tio) | Exabits (Ebit) |
|---|---|
| 1 Tebioctet | 0.00000879609302221 Ebit |
| 2 Tebioctets | 0.0000175921860444 Ebit |
| 3 Tebioctets | 0.0000263882790666 Ebit |
| 4 Tebioctets | 0.0000351843720888 Ebit |
| 5 Tebioctets | 0.000043980465111 Ebit |
| 10 Tebioctets | 0.0000879609302221 Ebit |
| 20 Tebioctets | 0.000175921860444 Ebit |
| 25 Tebioctets | 0.000219902325555 Ebit |
| 50 Tebioctets | 0.00043980465111 Ebit |
| 100 Tebioctets | 0.000879609302221 Ebit |
| Reference | Tebioctets (Tio) | Exabits (Ebit) |
|---|---|---|
| A plain text message (160 characters) | 1.45519 × 10-10 Tio | 1.28 × 10-15 Ebit |
| A three-minute MP3 | 0.00000272848 Tio | 2.4 × 10-11 Ebit |
| A smartphone photo | 0.00000363798 Tio | 3.2 × 10-11 Ebit |
| A high-definition film | 0.00363798 Tio | 0.000000032 Ebit |
| A dual-layer Blu-ray disc | 0.0454747 Tio | 0.0000004 Ebit |
The tebioctet is a unit of digital information equal to 1,099,511,627,776 octets, which is 1,024 gibioctets. Its symbol is Tio. It is the binary counterpart of the teraoctet, and at this level the two differ by 10 per cent — the gap that produces the most familiar complaint in consumer computing.
That complaint runs as follows. A drive is sold as one teraoctet, holds exactly one million million octets, and the operating system reports 931 gigaoctets. What it is actually reporting is 0.909 tebioctets, expressed with the wrong label. Nothing is missing from the drive; the number has simply been divided by 1,024 three times and then written with a decimal prefix.
Storage administration lives in this unit. Volume sizes, RAID array capacities, snapshot reserves and quota limits are all quoted in tebioctets by the tools that manage them, because the underlying allocation units are powers of two. A filesystem asked to create a 10-teraoctet volume and one asked to create a 10-tebioctet volume will produce visibly different results.
The difference matters commercially as well as technically. Cloud storage priced per teraoctet and cloud storage priced per tebioctet differ by a tenth in the quantity delivered for the same price, and a contract that does not say which is being used is genuinely ambiguous. Careful procurement documents specify the unit explicitly for exactly this reason.
A tebioctet holds around a quarter of a million photographs, two hundred hours of high-definition video, or the complete text of every book in a large public library many times over. In a household it is more storage than a lifetime of ordinary files will use; in a video production company it is a few days of work.
The correct symbol Tio appears in filesystem tools, in storage array documentation and in standards, and it is worth using even when the audience is unlikely to notice. A figure written with a binary prefix can be converted correctly by anyone who reads it later; one written ambiguously cannot be repaired.
One tebioctet equals 1,099,511,627,776 octets, 1,024 gibioctets, 8 tebibits, or about 1.100 teraoctets.
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.