| Kilooctets per second (ko/s) | Pebibits per second (Pibit/s) |
|---|---|
| 1 Kilooctet per second | 7.1054273576 × 10-12 Pibit/s |
| 2 Kilooctets per second | 1.42108547152 × 10-11 Pibit/s |
| 3 Kilooctets per second | 2.13162820728 × 10-11 Pibit/s |
| 4 Kilooctets per second | 2.84217094304 × 10-11 Pibit/s |
| 5 Kilooctets per second | 3.5527136788 × 10-11 Pibit/s |
| 10 Kilooctets per second | 7.1054273576 × 10-11 Pibit/s |
| 20 Kilooctets per second | 1.42108547152 × 10-10 Pibit/s |
| 25 Kilooctets per second | 1.7763568394 × 10-10 Pibit/s |
| 50 Kilooctets per second | 3.5527136788 × 10-10 Pibit/s |
| 100 Kilooctets per second | 7.1054273576 × 10-10 Pibit/s |
| Reference | Kilooctets per second (ko/s) | Pebibits per second (Pibit/s) |
|---|---|---|
| A dial-up modem | 7 ko/s | 4.9738 × 10-11 Pibit/s |
| Typical home broadband | 12500 ko/s | 0.0000000888178 Pibit/s |
| Gigabit Ethernet | 125000 ko/s | 0.000000888178 Pibit/s |
| Streaming a 4K film | 3125 ko/s | 0.0000000222045 Pibit/s |
The kilooctet per second is a unit of data transfer rate equal to one thousand octets per second, and therefore to eight kilobits per second. Its symbol is ko/s. It is the unit in which file transfers were reported through the whole of the dial-up era, and it still appears whenever a transfer is slow enough to need it.
The conversion from advertised connection speeds is the reason it matters. A 56-kilobit modem delivered about 7 kilooctets per second in practice, and users learned the relationship by watching progress bars: a one-megaoctet file took about two and a half minutes. The habit of dividing the advertised number by eight and then subtracting a bit for overhead dates from that period.
Storage devices of the era were similar. A floppy disc drive read at roughly 30 to 60 kilooctets per second, a single-speed compact-disc drive at 150, and an early hard drive at a few hundred. Loading a program from any of them was a matter of seconds to minutes, and software was written with that expectation in mind.
The unit still appears in serial communication. The classic serial port ran at rates up to 115,200 bits per second, which is 14.4 kilooctets per second, and equivalent rates are still used to talk to microcontrollers, scientific instruments and industrial equipment. A protocol designed for such a link cannot assume that a large message will arrive quickly.
It also appears at the bottom end of modern networking. A congested mobile connection, a distant satellite link or a heavily shared wireless network can fall to a few tens of kilooctets per second, and at that rate an ordinary web page — which now runs to a few megaoctets — takes a minute or more to load. The unit is a reminder of what the network assumes about its users.
For scale, one kilooctet per second moves a thousand characters of plain text each second, so a short letter transfers in a second and a novel in about ten minutes. Nothing about text has ever needed more than this; every increase in transfer rate since has been consumed by images, sound and video.
One kilooctet per second equals 1,000 octets per second, 8 kilobits per second, or about 0.9766 kibioctets per second.
The pebibit per second is a unit of data transfer rate equal to 1,024 tebibits per second, which is two to the fiftieth power bits per second. Its symbol is Pibit/s. It is the binary counterpart of the petabit per second, and the two differ by 12.6 per cent.
No deployed system runs at this rate, and the unit therefore describes either an aggregate or a laboratory result. Optical transmission records set on single fibres reach a petabit per second, and the binary figure for the same experiment is 12.6 per cent lower — a difference that matters when comparing results between papers that use different conventions.
Where the unit is genuinely appropriate is in describing structures built from powers of two. The total switching capacity of a very large network fabric, built from ports and buffers that are all binary, is a binary quantity divided by time, and reporting it in decimal units discards the arithmetic that produced it. The same applies to the summed memory bandwidth of a machine whose channel count is a power of two.
In octets a pebibit per second is 140,737,488,355,328, which is 128 tebioctets per second. That is the storage of a thousand large consumer drives moved every second, and it exists only as a total across many thousands of parallel paths inside a single facility.
The size of the discrepancy at this level is the argument for the whole IEC series in miniature. What began as a harmless 2.4 per cent at the kibibit is now an eighth, and it compounds by 2.4 per cent at every further step. A convention that was acceptable for small numbers becomes untenable for large ones, and the point of the binary prefixes is to make the distinction visible before that happens.
For a converter, the arithmetic is unremarkable: multiply or divide by 1,024 the appropriate number of times, and by eight to reach octets. What matters is that the tool does not silently substitute the decimal unit when it sees a value it cannot label precisely.
One pebibit per second equals 1,024 tebibits per second, 140,737,488,355,328 octets per second, or about 1.126 petabits per second.