| Kilobits (kbit) | Exaoctets (Eo) |
|---|---|
| 1 Kilobit | 1.25 × 10-16 Eo |
| 2 Kilobits | 2.5 × 10-16 Eo |
| 3 Kilobits | 3.75 × 10-16 Eo |
| 4 Kilobits | 5 × 10-16 Eo |
| 5 Kilobits | 6.25 × 10-16 Eo |
| 10 Kilobits | 1.25 × 10-15 Eo |
| 20 Kilobits | 2.5 × 10-15 Eo |
| 25 Kilobits | 3.125 × 10-15 Eo |
| 50 Kilobits | 6.25 × 10-15 Eo |
| 100 Kilobits | 1.25 × 10-14 Eo |
| Reference | Kilobits (kbit) | Exaoctets (Eo) |
|---|---|---|
| A plain text message (160 characters) | 1.28 kbit | 1.6 × 10-16 Eo |
| A three-minute MP3 | 24000 kbit | 3 × 10-12 Eo |
| A smartphone photo | 32000 kbit | 4 × 10-12 Eo |
| A high-definition film | 32000000 kbit | 0.000000004 Eo |
| A dual-layer Blu-ray disc | 400000000 kbit | 0.00000005 Eo |
The kilobit is a unit of digital information equal to one thousand bits. Its symbol is kbit. The lowercase k matters: it marks the decimal kilo of the metric system, one thousand exactly, as distinct from the binary 1,024 that the capital K sometimes indicated in older computing usage.
That distinction was fought over for decades. Memory is built in powers of two, so a chip holding 1,024 bits was called a kilobit chip, and the name stuck even though the number was wrong by 2.4 per cent. Storage and transmission, meanwhile, always counted in true thousands. The IEC settled the matter in 1998 by naming the binary quantity a kibibit, leaving the kilobit to mean one thousand and nothing else.
For a sense of scale, a kilobit holds 125 octets, which is about 125 characters of unaccented text — roughly a long sentence, or the length of a short social-media post. A single low-resolution photograph is thousands of times larger. The kilobit is a unit for things that were once considered generous and are now considered trivially small.
Its historical home was the telephone modem. Dial-up connections were rated in kilobits per second, and the numbers marked the era precisely: 300 bits per second in the late 1970s, then 1.2, 2.4, 9.6, 14.4, 28.8 and finally 56 kilobits per second, the last of which pushed an ordinary voice line to its theoretical ceiling. Anyone who used the internet before broadband measured their experience in these numbers.
The kilobit survives in audio and video encoding, where bit rates are quoted in kilobits per second. Speech codecs used in telephony run from 8 to 64. Music encoded at 128 kilobits per second was the early standard for portable players, 192 and 256 are common now, and 320 is the practical ceiling for the older lossy formats. Video runs a decimal order higher, in megabits.
Memory chip capacities are still occasionally described in kilobits, particularly for small serial memories used in embedded devices, where a 64-kilobit part holds 8 kilooctets of configuration data. In those specifications the figure is usually the binary one, so the datasheet is worth reading carefully.
One kilobit equals 1,000 bits, 125 octets, or about 0.9766 kibibits.
The exaoctet is a unit of digital information equal to a thousand petaoctets, or a billion gigaoctets. Its symbol is Eo. It is the unit in which the world's data flows and stockpiles are counted, and it belongs to civilisations rather than to companies or machines.
The most quoted figure involving it is global internet traffic, which passed one exaoctet per month around 2004 and now runs to several hundred exaoctets monthly. Written as an annual total that is several thousand exaoctets, which is why the zettaoctet was pressed into service for yearly figures a decade ago.
A frequently repeated claim holds that all the words ever spoken by human beings would amount to about five exaoctets in text. The estimate comes from a 2003 study and is very rough, but it makes the point: five exaoctets is now less than a fortnight of internet traffic. Whatever the exact number, the flow of data through the network long ago overtook the total of everything humanity has ever said.
Storage at exaoctet scale exists only at the largest cloud providers, and even there it is spread across dozens of buildings on several continents. The annual production of all the world's hard drives and flash memory together is a few hundred exaoctets, so the exaoctet is also the natural unit for describing the output of an entire industry.
What is stored at this scale is mostly not what people imagine. Backups, replicas, logs, telemetry, machine learning training corpora and video kept for regulatory reasons dominate. Deliberately created human work — documents, photographs, recordings that someone chose to make and keep — is a small and shrinking fraction of the whole.
The prefix exa has been part of the metric system since 1975, adopted at the same conference as peta. At the time these were prefixes without applications, defined for completeness. The fact that both became working units of a commercial industry within thirty years is the clearest single measure of how quickly digital information grew.
One exaoctet equals 1,000 petaoctets, 1,000,000,000 gigaoctets, 8 exabits, or about 0.8674 exbioctets.