| Kibibits per second (Kibit/s) | Exbibits per second (Eibit/s) |
|---|---|
| 1 Kibibit per second | 8.881784197 × 10-16 Eibit/s |
| 2 Kibibits per second | 1.7763568394 × 10-15 Eibit/s |
| 3 Kibibits per second | 2.6645352591 × 10-15 Eibit/s |
| 4 Kibibits per second | 3.5527136788 × 10-15 Eibit/s |
| 5 Kibibits per second | 4.4408920985 × 10-15 Eibit/s |
| 10 Kibibits per second | 8.881784197 × 10-15 Eibit/s |
| 20 Kibibits per second | 1.7763568394 × 10-14 Eibit/s |
| 25 Kibibits per second | 2.22044604925 × 10-14 Eibit/s |
| 50 Kibibits per second | 4.4408920985 × 10-14 Eibit/s |
| 100 Kibibits per second | 8.881784197 × 10-14 Eibit/s |
| Reference | Kibibits per second (Kibit/s) | Exbibits per second (Eibit/s) |
|---|---|---|
| A dial-up modem | 54.6875 Kibit/s | 4.85723 × 10-14 Eibit/s |
| Typical home broadband | 97656.2 Kibit/s | 8.67362 × 10-11 Eibit/s |
| Gigabit Ethernet | 976562 Kibit/s | 8.67362 × 10-10 Eibit/s |
| Streaming a 4K film | 24414.1 Kibit/s | 2.1684 × 10-11 Eibit/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 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.