| Mebibits per second (Mibit/s) | Exabits per second (Ebit/s) |
|---|---|
| 1 Mebibit per second | 1.048576 × 10-12 Ebit/s |
| 2 Mebibits per second | 2.097152 × 10-12 Ebit/s |
| 3 Mebibits per second | 3.145728 × 10-12 Ebit/s |
| 4 Mebibits per second | 4.194304 × 10-12 Ebit/s |
| 5 Mebibits per second | 5.24288 × 10-12 Ebit/s |
| 10 Mebibits per second | 1.048576 × 10-11 Ebit/s |
| 20 Mebibits per second | 2.097152 × 10-11 Ebit/s |
| 25 Mebibits per second | 2.62144 × 10-11 Ebit/s |
| 50 Mebibits per second | 5.24288 × 10-11 Ebit/s |
| 100 Mebibits per second | 1.048576 × 10-10 Ebit/s |
| Reference | Mebibits per second (Mibit/s) | Exabits per second (Ebit/s) |
|---|---|---|
| A dial-up modem | 0.0534058 Mibit/s | 5.6 × 10-14 Ebit/s |
| Typical home broadband | 95.3674 Mibit/s | 1 × 10-10 Ebit/s |
| Gigabit Ethernet | 953.674 Mibit/s | 0.000000001 Ebit/s |
| Streaming a 4K film | 23.8419 Mibit/s | 2.5 × 10-11 Ebit/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 exabit per second is a unit of data transfer rate equal to a thousand petabits per second. Its symbol is Ebit/s. No link, no cable and no exchange point runs at this rate; the unit describes the internet as a whole, or a large part of it, at a single instant.
Global internet traffic can be expressed this way. Worldwide traffic of several hundred exaoctets a month works out to roughly one exabit per second on average, and peak hours run higher. That figure is the sum of every packet moving on every network on the planet, and it is the only quantity anyone routinely describes at this scale.
An exabit per second is 125 petaoctets per second. Nothing generates data at that rate in one place; the number is an aggregate of billions of separate flows, most of them tiny. A single video stream is a few megabits per second, so an exabit per second is on the order of a hundred million such streams running at once.
The composition of that traffic is dominated by video. Streaming services account for the largest share, followed by social platforms, software updates and cloud synchronisation. Ordinary web browsing and messaging, which people think of as the internet, are a small fraction of the total by volume even though they occupy most of the attention.
The unit also appears in projections of aggregate capacity. The total installed capacity of all submarine cables, if every wavelength on every fibre pair were lit and used simultaneously, is in the exabit-per-second range. Actual utilisation is far below that, because capacity is built ahead of demand and because routes must carry each other's traffic when a cable fails.
The prefix exa is a thousand to the sixth power. It was adopted in 1975, when nobody expected it to describe anything but astronomical quantities, and it now describes the working throughput of a communications system built by human beings. The interval between definition and everyday use was about forty years.
One exabit per second equals 1,000 petabits per second, 125 petaoctets per second, or about 0.8674 exbibits per second.