| Megabits per second (Mbit/s) | Exbibits per second (Eibit/s) |
|---|---|
| 1 Megabit per second | 8.67361737988 × 10-13 Eibit/s |
| 2 Megabits per second | 1.73472347598 × 10-12 Eibit/s |
| 3 Megabits per second | 2.60208521397 × 10-12 Eibit/s |
| 4 Megabits per second | 3.46944695195 × 10-12 Eibit/s |
| 5 Megabits per second | 4.33680868994 × 10-12 Eibit/s |
| 10 Megabits per second | 8.67361737988 × 10-12 Eibit/s |
| 20 Megabits per second | 1.73472347598 × 10-11 Eibit/s |
| 25 Megabits per second | 2.16840434497 × 10-11 Eibit/s |
| 50 Megabits per second | 4.33680868994 × 10-11 Eibit/s |
| 100 Megabits per second | 8.67361737988 × 10-11 Eibit/s |
| Reference | Megabits per second (Mbit/s) | Exbibits per second (Eibit/s) |
|---|---|---|
| A dial-up modem | 0.056 Mbit/s | 4.85723 × 10-14 Eibit/s |
| Typical home broadband | 100 Mbit/s | 8.67362 × 10-11 Eibit/s |
| Gigabit Ethernet | 1000 Mbit/s | 8.67362 × 10-10 Eibit/s |
| Streaming a 4K film | 25 Mbit/s | 2.1684 × 10-11 Eibit/s |
The megabit per second is a unit of data transfer rate equal to one million bits per second. Its symbol is Mbit/s, often written Mbps. It is the unit in which internet connections are sold, which makes it the data unit most people encounter by name.
Because it is a decimal million and not 1,048,576, the conversion to octets is exact and easy: one megabit per second is 125 kilooctets per second, so a hundred-megabit connection delivers about 12.5 megaoctets per second at best. Anyone who watches a file transfer and does the division has understood the entire relationship between how connections are advertised and how transfers are reported.
What a household actually needs is far below what it usually buys. Standard-definition video streaming uses about 3 megabits per second, high definition about 5, and ultra-high definition about 25. A video call is around 3 to 8. A large family watching four separate high-definition streams while somebody downloads a game is using perhaps 60 megabits per second, which a hundred-megabit connection handles comfortably.
The reason to buy more capacity than that is not peak speed but behaviour under load. A link that is near its limit develops queues, and queues add delay, which shows up as stutter in video calls and lag in games. A connection with generous headroom keeps its latency low, and that is a more noticeable improvement than a higher number on a speed test.
Wired local networks pass through this range on the way up. The original Ethernet ran at 10 megabits per second, its successor at 100, and both were the standard office connection for a decade each before gigabit replaced them. Wireless standards followed the same path with a lag, and both are now measured in hundreds of megabits or in gigabits.
Real throughput is always below the nominal rate. Protocol overhead takes 5 to 10 per cent on a wired link; a shared wireless channel loses much more, because the medium is divided between all the devices using it and interference forces retransmission. A connection advertised at 100 megabits per second measured at 90 over cable and 50 over a busy wireless network is behaving normally.
One megabit per second equals 1,000,000 bits per second, 125 kilooctets per second, or about 0.9537 mebibits 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.