| Mebioctets per second (Mio/s) | Yottabits per second (Ybit/s) |
|---|---|
| 1 Mebioctet per second | 8.388608 × 10-18 Ybit/s |
| 2 Mebioctets per second | 1.6777216 × 10-17 Ybit/s |
| 3 Mebioctets per second | 2.5165824 × 10-17 Ybit/s |
| 4 Mebioctets per second | 3.3554432 × 10-17 Ybit/s |
| 5 Mebioctets per second | 4.194304 × 10-17 Ybit/s |
| 10 Mebioctets per second | 8.388608 × 10-17 Ybit/s |
| 20 Mebioctets per second | 1.6777216 × 10-16 Ybit/s |
| 25 Mebioctets per second | 2.097152 × 10-16 Ybit/s |
| 50 Mebioctets per second | 4.194304 × 10-16 Ybit/s |
| 100 Mebioctets per second | 8.388608 × 10-16 Ybit/s |
| Reference | Mebioctets per second (Mio/s) | Yottabits per second (Ybit/s) |
|---|---|---|
| A dial-up modem | 0.00667572 Mio/s | 5.6 × 10-20 Ybit/s |
| Typical home broadband | 11.9209 Mio/s | 1 × 10-16 Ybit/s |
| Gigabit Ethernet | 119.209 Mio/s | 1 × 10-15 Ybit/s |
| Streaming a 4K film | 2.98023 Mio/s | 2.5 × 10-17 Ybit/s |
The mebioctet per second is a unit of data transfer rate equal to 1,048,576 octets per second, which is 1,024 kibioctets per second. Its symbol is Mio/s. It is the unit that disc benchmarks, copy tools and backup programs report in, and one of the few binary units most people see regularly without noticing.
Storage measurement produces it naturally. A benchmark writes and reads blocks whose size is a power of two, times the operation, and divides. The result is a binary rate, and reporting it as such preserves the arithmetic. A tool that converted to decimal megaoctets would introduce a 4.9 per cent adjustment for no purpose other than to match a marketing convention.
That five per cent is exactly where the two conventions diverge visibly for consumers. A drive advertised at 550 megaoctets per second and measured at 524 mebioctets per second is performing precisely as claimed; the numbers differ only because one is decimal and the other binary. A great deal of complaint about storage performance is this arithmetic misread as a shortfall.
For everyday sizes, one mebioctet per second copies a photograph in three seconds and a two-gigaoctet film in about half an hour. Modern drives run hundreds or thousands of times faster, so the unit is now the resolution at which small differences are reported rather than the scale of the whole figure.
The unit also appears in memory and cache measurements, in database throughput reports and in the output of the low-level commands that write disc images. All of these count in binary blocks because the underlying structures are binary, and all of them report in mebioctets per second because that is what the count divided by the time actually gives.
The habit of writing the lowercase i is worth keeping. It costs one character and it tells a later reader which of two conventions produced the number, which is information that cannot be recovered from context once it has been left out.
One mebioctet per second equals 1,048,576 octets per second, 1,024 kibioctets per second, or about 1.049 megaoctets per second.
The yottabit per second is a unit of data transfer rate equal to a thousand zettabits per second. Its symbol is Ybit/s. For thirty years it was the largest rate the metric system could name, and it describes a speed that has no application anywhere: not in engineering, not in research, and not in any forecast that anyone takes seriously.
Its distance from reality is easy to state. Global internet traffic averages roughly one exabit per second, so a yottabit per second is about a million times the combined communication of the entire human species. The largest single link ever built runs at a few hundred terabits per second, which is a ten-billionth of this figure.
The unit is nonetheless properly defined, and that completeness is the point. The metric system's rule is that every prefix combines with every unit without exception, so a reader who has never seen Ybit/s can decode it from the prefix alone. A system with gaps would need a table of which combinations are legal, and a table is exactly what a rule-based system exists to avoid.
There is a physical way to think about the number. A yottabit per second is 125 zettaoctets per second, and the total quantity of data humanity has ever stored is a few hundred zettaoctets. A link at this rate would therefore transmit the entire accumulated information of the species in a couple of seconds. No such body of data exists in one place to be sent, and nothing at the far end could receive it.
The prefix yotta was adopted in 1991 alongside zetta, at a conference that also had to consider which letters remained free. It stood at the top of the metric ladder until 2022, when ronna and quetta were added above it, partly because data quantities were beginning to approach the old ceiling. Rates have not followed quantities upward at the same pace.
For a converter, handling the unit is a matter of consistency rather than utility. A tool that converts every metric prefix correctly does not need to decide which of them anyone will use, and a figure written in yottabits per second — however unlikely — converts by the same rule as any other.
One yottabit per second equals 1,000 zettabits per second, 125 zettaoctets per second, or about 0.8272 yobibits per second.