| Exabits per second (Ebit/s) | Kibioctets per second (Kio/s) |
|---|---|
| 1 Exabit per second | 122070312500000 Kio/s |
| 2 Exabits per second | 244140625000000 Kio/s |
| 3 Exabits per second | 366210937500000 Kio/s |
| 4 Exabits per second | 488281250000000 Kio/s |
| 5 Exabits per second | 610351562500000 Kio/s |
| 10 Exabits per second | 1.220703125 × 1015 Kio/s |
| 20 Exabits per second | 2.44140625 × 1015 Kio/s |
| 25 Exabits per second | 3.0517578125 × 1015 Kio/s |
| 50 Exabits per second | 6.103515625 × 1015 Kio/s |
| 100 Exabits per second | 1.220703125 × 1016 Kio/s |
| Reference | Exabits per second (Ebit/s) | Kibioctets per second (Kio/s) |
|---|---|---|
| A dial-up modem | 5.6 × 10-14 Ebit/s | 6.83594 Kio/s |
| Typical home broadband | 1 × 10-10 Ebit/s | 12207 Kio/s |
| Gigabit Ethernet | 0.000000001 Ebit/s | 122070 Kio/s |
| Streaming a 4K film | 2.5 × 10-11 Ebit/s | 3051.76 Kio/s |
The exabit per second is a unit of data transfer rate equal to a thousand petabits per second. Its symbol is Ebit/s. No link, no cable and no exchange point runs at this rate; the unit describes the internet as a whole, or a large part of it, at a single instant.
Global internet traffic can be expressed this way. Worldwide traffic of several hundred exaoctets a month works out to roughly one exabit per second on average, and peak hours run higher. That figure is the sum of every packet moving on every network on the planet, and it is the only quantity anyone routinely describes at this scale.
An exabit per second is 125 petaoctets per second. Nothing generates data at that rate in one place; the number is an aggregate of billions of separate flows, most of them tiny. A single video stream is a few megabits per second, so an exabit per second is on the order of a hundred million such streams running at once.
The composition of that traffic is dominated by video. Streaming services account for the largest share, followed by social platforms, software updates and cloud synchronisation. Ordinary web browsing and messaging, which people think of as the internet, are a small fraction of the total by volume even though they occupy most of the attention.
The unit also appears in projections of aggregate capacity. The total installed capacity of all submarine cables, if every wavelength on every fibre pair were lit and used simultaneously, is in the exabit-per-second range. Actual utilisation is far below that, because capacity is built ahead of demand and because routes must carry each other's traffic when a cable fails.
The prefix exa is a thousand to the sixth power. It was adopted in 1975, when nobody expected it to describe anything but astronomical quantities, and it now describes the working throughput of a communications system built by human beings. The interval between definition and everyday use was about forty years.
One exabit per second equals 1,000 petabits per second, 125 petaoctets per second, or about 0.8674 exbibits per second.
The kibioctet per second is a unit of data transfer rate equal to 1,024 octets per second, and therefore to 8,192 bits per second. Its symbol is Kio/s. Unlike most of the binary rate units it is genuinely common, because the command-line tools that copy, download and synchronise files have reported in it for decades.
The reason is straightforward. Those tools count what they have moved in blocks, and blocks are powers of two. A program that reads in four-kibioctet pieces and divides the total by elapsed time produces a rate in kibioctets per second, and reporting it in decimal kilooctets would require an extra multiplication for no benefit. The unit is what the arithmetic naturally produces.
Anyone who has watched a file copy on a Unix-like system has seen the figure. Download utilities, archive tools, disc-writing commands and network file transfer programs all report progress in kibioctets or mebioctets per second, and most of them label it correctly with the lowercase i. It is one of the few places where the IEC prefixes are used consistently in everyday software.
For scale, a kibioctet per second moves about a thousand characters of text each second: a short letter in a second, a novel in about ten minutes. It is a rate at which a modern web page will not load in any reasonable time, so seeing it in a progress display usually means something has gone wrong with the connection rather than that the transfer is nearly finished.
The difference from a kilooctet per second is 2.4 per cent, which nobody notices. The value of using the binary unit here is not accuracy but honesty: the number came from a binary computation, and writing it with a binary prefix says so. A reader who wants the decimal figure can convert; a reader given a decimal label for a binary number cannot recover anything.
Comparing the reading with an advertised connection speed requires two steps: multiply by eight to get bits, and adjust by 2.4 per cent for the base. In practice the second step is beneath the noise of any real measurement, and the first is the one that matters.
One kibioctet per second equals 1,024 octets per second, 8,192 bits per second, or 1.024 kilooctets per second.