| Kibibits per second (Kibit/s) | Petabits per second (Pbit/s) |
|---|---|
| 1 Kibibit per second | 1.024 × 10-12 Pbit/s |
| 2 Kibibits per second | 2.048 × 10-12 Pbit/s |
| 3 Kibibits per second | 3.072 × 10-12 Pbit/s |
| 4 Kibibits per second | 4.096 × 10-12 Pbit/s |
| 5 Kibibits per second | 5.12 × 10-12 Pbit/s |
| 10 Kibibits per second | 1.024 × 10-11 Pbit/s |
| 20 Kibibits per second | 2.048 × 10-11 Pbit/s |
| 25 Kibibits per second | 2.56 × 10-11 Pbit/s |
| 50 Kibibits per second | 5.12 × 10-11 Pbit/s |
| 100 Kibibits per second | 1.024 × 10-10 Pbit/s |
| Reference | Kibibits per second (Kibit/s) | Petabits per second (Pbit/s) |
|---|---|---|
| A dial-up modem | 54.6875 Kibit/s | 5.6 × 10-11 Pbit/s |
| Typical home broadband | 97656.2 Kibit/s | 0.0000001 Pbit/s |
| Gigabit Ethernet | 976562 Kibit/s | 0.000001 Pbit/s |
| Streaming a 4K film | 24414.1 Kibit/s | 0.000000025 Pbit/s |
The kibibit per second is a unit of data transfer rate equal to 1,024 bits per second. Its symbol is Kibit/s. It is the binary counterpart of the kilobit per second, and it is the least used member of an already unusual family, because transfer rates are one of the few places in computing where the decimal convention has always been unambiguous.
Networking has counted in true thousands from the beginning. A modem rated at 56 kilobits per second meant fifty-six thousand, not fifty-seven thousand three hundred and forty-four. The reason is that a transmission rate is set by a clock, and clocks are specified in decimal frequencies: a link running at ten million symbols per second carries a decimal number of bits, not a power of two.
The binary prefixes exist for quantities, not for rates, because quantities of storage are organised in powers of two while time is not. There is no natural reason for a rate to be a power of two, and consequently no reason for a rate unit to need a binary prefix. Where one appears, it is almost always because a program divided a binary file size by a duration.
That is exactly where the kibibit per second does turn up. A tool that measures a transfer by counting kibioctets and dividing by seconds produces a rate in kibioctets per second, and multiplying by eight gives kibibits per second. The unit is a consequence of the arithmetic rather than a description of the channel.
For scale, a kibibit per second is 128 octets per second, and the difference from a kilobit per second is 2.4 per cent — smaller than the measurement error of almost any real throughput test. At this level the distinction is technically correct and practically invisible, which is a fair description of the whole binary prefix system at its lower end.
The unit is properly defined and a converter must handle it, because the IEC series applies to every unit without exception. Whether anyone writes it is a separate question from whether it means something definite, and it does.
One kibibit per second equals 1,024 bits per second, 128 octets per second, or 1.024 kilobits per second.
The petabit per second is a unit of data transfer rate equal to a thousand terabits per second. Its symbol is Pbit/s. It marks the frontier of optical transmission research: the rate at which laboratories have carried data down a single strand of glass, and which no deployed system yet approaches.
The records were set by combining three techniques. Multi-core fibre puts several separate light-guiding paths inside one cladding, so that a single strand behaves like a bundle. Wavelength division multiplexing runs hundreds of distinct colours down each of those cores. Advanced modulation encodes many bits into each pulse. Multiplying the three together is what reaches a petabit per second.
Such demonstrations run over tens of kilometres of fibre in controlled conditions, not the thousands of kilometres a working sea cable must span. Distance is the hard part: signals attenuate, dispersion smears pulses together, and non-linear effects in the glass grow with power. Every kilometre added makes the same rate harder to sustain, which is why deployed cables sit two orders of magnitude below the laboratory record.
In octets a petabit per second is 125 teraoctets per second, which is roughly the storage of a hundred and twenty-five large hard drives moved every second. Nothing at either end of such a link could produce or absorb data at that rate; the figure describes the medium's capacity rather than any use of it.
At the network level the unit is used for aggregates. The total interconnect capacity of a very large data centre, the summed capacity of all the cables landing on a continent, and the peak traffic of the largest content networks are quoted in petabits per second. These are sums over thousands of links, not the rating of any one.
The trajectory is worth noting. Transoceanic capacity has grown by roughly a factor of ten every seven or eight years for several decades, driven almost entirely by better electronics and better coding rather than by more glass. If that continues, the petabit per second will describe a working cable within a generation.
One petabit per second equals 1,000 terabits per second, 125 teraoctets per second, or about 0.8882 pebibits per second.