| Megaoctets per second (Mo/s) | Exbibits per second (Eibit/s) |
|---|---|
| 1 Megaoctet per second | 6.93889390391 × 10-12 Eibit/s |
| 2 Megaoctets per second | 1.38777878078 × 10-11 Eibit/s |
| 3 Megaoctets per second | 2.08166817117 × 10-11 Eibit/s |
| 4 Megaoctets per second | 2.77555756156 × 10-11 Eibit/s |
| 5 Megaoctets per second | 3.46944695195 × 10-11 Eibit/s |
| 10 Megaoctets per second | 6.93889390391 × 10-11 Eibit/s |
| 20 Megaoctets per second | 1.38777878078 × 10-10 Eibit/s |
| 25 Megaoctets per second | 1.73472347598 × 10-10 Eibit/s |
| 50 Megaoctets per second | 3.46944695195 × 10-10 Eibit/s |
| 100 Megaoctets per second | 6.93889390391 × 10-10 Eibit/s |
| Reference | Megaoctets per second (Mo/s) | Exbibits per second (Eibit/s) |
|---|---|---|
| A dial-up modem | 0.007 Mo/s | 4.85723 × 10-14 Eibit/s |
| Typical home broadband | 12.5 Mo/s | 8.67362 × 10-11 Eibit/s |
| Gigabit Ethernet | 125 Mo/s | 8.67362 × 10-10 Eibit/s |
| Streaming a 4K film | 3.125 Mo/s | 2.1684 × 10-11 Eibit/s |
The megaoctet per second is a unit of data transfer rate equal to one million octets per second, or eight megabits per second. Its symbol is Mo/s. It is the unit in which storage devices and their interfaces are rated, and the one a file manager shows while a copy is running.
Storage speeds fall naturally into this range. A mechanical hard drive sustains 100 to 250 megaoctets per second on sequential reads. A solid-state drive on the older interface reaches about 550, which is the limit of that interface rather than of the drive. A modern drive on the faster interface reaches several thousand, at which point the unit gives way to gigaoctets per second.
Interface speeds tell the same story from the other side. The successive versions of the universal serial bus have offered roughly 1.5, 60, 625 and 2,500 megaoctets per second at their nominal rates, and memory card standards have followed a similar path. A device is always limited by whichever of the two is slower, and matching them is the practical art of building a fast system.
For everyday sizes, one megaoctet per second transfers a photograph in a couple of seconds and a two-gigaoctet film in about half an hour. At 500 megaoctets per second the same film takes four seconds. That contrast explains why the perceived speed of a computer changed so completely when solid-state storage replaced mechanical drives, even though processors improved far less over the same period.
Sequential rates like these are the best case. Reading many small files instead of one large one costs far more, because each file requires locating its data and reading its record. A drive that sustains 500 megaoctets per second in sequence may manage only a few tens when copying a directory of thousands of small files, and that is where the difference between drive technologies is most visible.
The unit also describes the throughput of a busy network connection: a gigabit link delivers 125 megaoctets per second at best, so a fast local network and a fast drive are now comparable, and neither is obviously the limiting factor in a transfer.
One megaoctet per second equals 1,000,000 octets per second, 8 megabits per second, or about 0.9537 mebioctets 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.