| Kibibits per second (Kibit/s) | Zebioctets per second (Zio/s) |
|---|---|
| 1 Kibibit per second | 1.08420217249 × 10-19 Zio/s |
| 2 Kibibits per second | 2.16840434497 × 10-19 Zio/s |
| 3 Kibibits per second | 3.25260651746 × 10-19 Zio/s |
| 4 Kibibits per second | 4.33680868994 × 10-19 Zio/s |
| 5 Kibibits per second | 5.42101086243 × 10-19 Zio/s |
| 10 Kibibits per second | 1.08420217249 × 10-18 Zio/s |
| 20 Kibibits per second | 2.16840434497 × 10-18 Zio/s |
| 25 Kibibits per second | 2.71050543121 × 10-18 Zio/s |
| 50 Kibibits per second | 5.42101086243 × 10-18 Zio/s |
| 100 Kibibits per second | 1.08420217249 × 10-17 Zio/s |
| Reference | Kibibits per second (Kibit/s) | Zebioctets per second (Zio/s) |
|---|---|---|
| A dial-up modem | 54.6875 Kibit/s | 5.92923 × 10-18 Zio/s |
| Typical home broadband | 97656.2 Kibit/s | 1.05879 × 10-14 Zio/s |
| Gigabit Ethernet | 976562 Kibit/s | 1.05879 × 10-13 Zio/s |
| Streaming a 4K film | 24414.1 Kibit/s | 2.64698 × 10-15 Zio/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 zebioctet per second is a unit of data transfer rate equal to 1,024 exbioctets per second, or two to the seventieth power octets per second. Its symbol is Zio/s. It is the binary counterpart of the zettaoctet per second, and the two differ by 18.1 per cent.
A link running at this rate would transfer everything humanity has ever stored several times over in a single second. That is the plainest way to describe how far it lies beyond anything that exists, is planned, or has been seriously proposed. The unit is a name for a quantity, not a description of a thing.
It is worth being precise about why such names are still defined. A measurement system is a set of rules, and the value of a rule is that it applies without exception. The moment a system says that certain prefix-and-unit combinations are legal and others are not, every user must carry a table instead of a rule, and different users will carry different tables. Complete definition is cheaper and safer.
The physical obstacles are not merely large but qualitative. At a zebioctet per second, the energy needed to switch the required number of states, even at the thermodynamic minimum, becomes a substantial power; the practical figure for real electronics is many orders of magnitude above that; and the number of parallel channels required exceeds anything that could be built and cooled. These are not engineering targets.
The 18.1 per cent gap from the decimal unit continues the pattern that runs through the whole binary series. Each step multiplies the discrepancy by 1.024, so a convention that was harmless at the kibioctet has become, by this point, a difference no reader could overlook. Making that visible is the purpose the IEC prefixes serve.
In practice, a converter meets this unit only in a complete table or in a document exploring theoretical limits. Handling it correctly costs nothing and demonstrates that the tool applies its rules uniformly, which is the property that makes its ordinary answers trustworthy.
One zebioctet per second equals 1,024 exbioctets per second, 1,180,591,620,717,411,303,424 octets per second, or about 1.181 zettaoctets per second.