| Mebibits per second (Mibit/s) | Yobioctets per second (Yio/s) |
|---|---|
| 1 Mebibit per second | 1.08420217249 × 10-19 Yio/s |
| 2 Mebibits per second | 2.16840434497 × 10-19 Yio/s |
| 3 Mebibits per second | 3.25260651746 × 10-19 Yio/s |
| 4 Mebibits per second | 4.33680868994 × 10-19 Yio/s |
| 5 Mebibits per second | 5.42101086243 × 10-19 Yio/s |
| 10 Mebibits per second | 1.08420217249 × 10-18 Yio/s |
| 20 Mebibits per second | 2.16840434497 × 10-18 Yio/s |
| 25 Mebibits per second | 2.71050543121 × 10-18 Yio/s |
| 50 Mebibits per second | 5.42101086243 × 10-18 Yio/s |
| 100 Mebibits per second | 1.08420217249 × 10-17 Yio/s |
| Reference | Mebibits per second (Mibit/s) | Yobioctets per second (Yio/s) |
|---|---|---|
| A dial-up modem | 0.0534058 Mibit/s | 5.79026 × 10-21 Yio/s |
| Typical home broadband | 95.3674 Mibit/s | 1.03398 × 10-17 Yio/s |
| Gigabit Ethernet | 953.674 Mibit/s | 1.03398 × 10-16 Yio/s |
| Streaming a 4K film | 23.8419 Mibit/s | 2.58494 × 10-18 Yio/s |
The mebibit per second is a unit of data transfer rate equal to 1,048,576 bits per second. Its symbol is Mibit/s. It is the binary counterpart of the megabit per second, and the two differ by 4.9 per cent — small, but large enough to change a headline figure.
That five per cent is where the unit starts to matter. A connection advertised at 100 megabits per second and a connection at 100 mebibits per second differ by about five megabits, which is a whole high-definition video stream. In a specification, a contract or a benchmark report, quoting one and delivering the other is a real discrepancy rather than a rounding difference.
In practice the confusion is rare in networking, because network equipment is always specified in decimal. What produces mebibit figures is measurement software: a tool that counts a transfer in mebioctets and divides by elapsed seconds is reporting a binary rate, and multiplying by eight makes it mebibits per second. A person comparing that reading with an advertised rate must convert twice, once for the base and once for the factor of eight.
Where a genuine binary rate does arise is inside a machine. A memory bus transfers a fixed number of bits per clock cycle, and the width is a power of two — sixty-four bits at a time, for instance — so the quantity moved per cycle is binary even though the clock frequency is not. Rates derived from such a structure are naturally expressed with binary prefixes.
For scale, a mebibit per second is 131,072 octets per second, or about 128 kibioctets per second. That is roughly a photograph every two seconds, or a plain-text novel every four. It is a rate at which the modern web is slow but usable, which puts it in the range that mobile networks fall to when congested.
The correct symbol has the lowercase i, and its presence is the only reliable way to tell the two conventions apart. A document writing Mbit/s in a context where the underlying figure came from a binary computation has misstated its own measurement by five per cent.
One mebibit per second equals 1,048,576 bits per second, 131,072 octets per second, or about 1.049 megabits per second.
The yobioctet per second is a unit of data transfer rate equal to 1,024 zebioctets per second, or two to the eightieth power octets per second. Its symbol is Yio/s. It is the largest binary rate the International Electrotechnical Commission has named, and the last rung of the ladder that began with the bit per second.
At this final step the binary and decimal conventions differ by 20.9 per cent. That figure closes the argument the IEC prefixes were created to settle: a naming habit that was 2.4 per cent wrong at the kibibit per second has grown, through eight successive multiplications by 1.024, into a discrepancy of more than a fifth. No system of measurement can carry an ambiguity that large, and the whole binary series exists to remove it.
The rate itself has no referent. A yobioctet per second is more than eight million times the total instantaneous traffic of the internet, and it would transfer everything humanity has ever stored several thousand times over in a second. Nothing produces data at that rate, nothing consumes it, and nothing is designed with it in view.
That does not make the unit pointless. Defining the whole ladder in advance means that the rule — every prefix combines with every unit — is all anyone has to learn, and a rule is easier to carry than a table of exceptions. The same principle gave the metric system its complete prefix set, and the addition of ronna and quetta in 2022 extended the decimal side without any matching binary names being defined.
The practical value of a unit like this is that it makes a converter's behaviour uniform. A tool that handles the impossible cases by the same rule as the ordinary ones can be trusted not to have special cases hidden in it, and that is a property worth having in something whose whole purpose is to be relied upon.
For the reader, the whole series comes down to one character: Kio/s, Mio/s, Gio/s, Tio/s, Pio/s, Eio/s, Zio/s and Yio/s are binary; ko/s, Mo/s, Go/s, To/s, Po/s, Eo/s, Zo/s and Yo/s are decimal; and the difference between them widens from a rounding error to a fifth as you climb.
One yobioctet per second equals 1,024 zebioctets per second, 1,208,925,819,614,629,174,706,176 octets per second, or about 1.209 yottaoctets per second.