| Kibioctets per second (Kio/s) | Exbibits per second (Eibit/s) |
|---|---|
| 1 Kibioctet per second | 7.1054273576 × 10-15 Eibit/s |
| 2 Kibioctets per second | 1.42108547152 × 10-14 Eibit/s |
| 3 Kibioctets per second | 2.13162820728 × 10-14 Eibit/s |
| 4 Kibioctets per second | 2.84217094304 × 10-14 Eibit/s |
| 5 Kibioctets per second | 3.5527136788 × 10-14 Eibit/s |
| 10 Kibioctets per second | 7.1054273576 × 10-14 Eibit/s |
| 20 Kibioctets per second | 1.42108547152 × 10-13 Eibit/s |
| 25 Kibioctets per second | 1.7763568394 × 10-13 Eibit/s |
| 50 Kibioctets per second | 3.5527136788 × 10-13 Eibit/s |
| 100 Kibioctets per second | 7.1054273576 × 10-13 Eibit/s |
| Reference | Kibioctets per second (Kio/s) | Exbibits per second (Eibit/s) |
|---|---|---|
| A dial-up modem | 6.83594 Kio/s | 4.85723 × 10-14 Eibit/s |
| Typical home broadband | 12207 Kio/s | 8.67362 × 10-11 Eibit/s |
| Gigabit Ethernet | 122070 Kio/s | 8.67362 × 10-10 Eibit/s |
| Streaming a 4K film | 3051.76 Kio/s | 2.1684 × 10-11 Eibit/s |
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.
The exbibit per second is a unit of data transfer rate equal to two to the sixtieth power bits per second, which is 1,024 pebibits per second. Its symbol is Eibit/s. It is the binary counterpart of the exabit per second, and the two differ by 15.3 per cent.
That fifteen per cent is more than the margin most engineering work allows anywhere. A quantity stated in the wrong convention at this level is not slightly imprecise but plainly wrong, and no amount of context recovers the intended figure once it has been written ambiguously. This is the situation the IEC prefixes were introduced to prevent.
No physical link approaches this rate. The unit describes aggregates: the total instantaneous traffic of the whole internet is roughly an exabit per second, so a binary exbibit per second is fifteen per cent more than everything moving on every network on the planet at a given moment.
Where a binary figure of this size arises naturally is in address arithmetic rather than in transmission. Two to the sixtieth is a number that appears throughout the design of 64-bit systems, and any rate derived from filling or traversing such an address space in a fixed time is naturally binary. Those calculations are theoretical, but they are the reason the unit is defined rather than left unnamed.
In octets an exbibit per second is 144,115,188,075,855,872, or 128 pebioctets per second. That is more storage moved per second than the world manufactures in several years, which is a way of saying that no source and no destination for such a flow could exist.
For a converter the treatment is mechanical and must be exact. Eibit/s and Ebit/s differ by an eighth, and a tool that treats them as interchangeable has introduced an error larger than the difference between many neighbouring units. The lowercase i is not decoration.
One exbibit per second equals 1,024 pebibits per second, 144,115,188,075,855,872 octets per second, or about 1.153 exabits per second.