| Mebibits (Mibit) | Tebioctets (Tio) |
|---|---|
| 1 Mebibit | 0.000000119209289551 Tio |
| 2 Mebibits | 0.000000238418579102 Tio |
| 3 Mebibits | 0.000000357627868652 Tio |
| 4 Mebibits | 0.000000476837158203 Tio |
| 5 Mebibits | 0.000000596046447754 Tio |
| 10 Mebibits | 0.00000119209289551 Tio |
| 20 Mebibits | 0.00000238418579102 Tio |
| 25 Mebibits | 0.00000298023223877 Tio |
| 50 Mebibits | 0.00000596046447754 Tio |
| 100 Mebibits | 0.0000119209289551 Tio |
| Reference | Mebibits (Mibit) | Tebioctets (Tio) |
|---|---|---|
| A plain text message (160 characters) | 0.0012207 Mibit | 1.45519 × 10-10 Tio |
| A three-minute MP3 | 22.8882 Mibit | 0.00000272848 Tio |
| A smartphone photo | 30.5176 Mibit | 0.00000363798 Tio |
| A high-definition film | 30517.6 Mibit | 0.00363798 Tio |
| A dual-layer Blu-ray disc | 381470 Mibit | 0.0454747 Tio |
The mebibit is a unit of digital information equal to 1,048,576 bits, which is 1,024 kibibits or two to the twentieth power. Its symbol is Mibit. It is the binary counterpart of the megabit, and the difference between the two has grown to 4.9 per cent — small enough to be ignored casually, large enough to matter in a specification.
Its natural home is semiconductor memory, where capacity is fixed by the address lines on the chip. A memory die with twenty address bits can reach exactly 1,048,576 locations, so densities land on powers of two rather than on round decimal numbers. A chip described as 512 megabits in a catalogue is very often 512 mebibits in reality, which is 537 megabits, and the datasheet is where the truth is written.
That habit is old and deliberate. Semiconductor manufacturers have always sized memory in binary because the wiring makes any other choice wasteful: an address bus is a fixed number of lines, and using only part of the range it can reach throws away silicon. Storage manufacturers had no such constraint, which is precisely why the two industries diverged.
For a sense of quantity, a mebibit is 131,072 octets, or about 128 kibioctets. That is roughly the contents of a long book as plain text, or a single low-resolution image. In network terms it is a hundredth of a second of a gigabit link.
The IEC prefixes were introduced in 1998 partly because at this level and above the approximation stops being safe. Buying a component described as one megabit and receiving one mebibit is a five per cent surprise; at the tebibit the same confusion is a ten per cent surprise, and in a contract for a data centre that is a real sum of money.
Correct usage is now common in standards documents, in hardware datasheets and in operating system internals, and rare in advertising and consumer software. The best rule when reading a figure is to ask which industry produced it: if it describes memory or a chip, assume binary; if it describes storage or a link, assume decimal.
One mebibit equals 1,048,576 bits, 1,024 kibibits, 131,072 octets, or about 1.049 megabits.
The tebioctet is a unit of digital information equal to 1,099,511,627,776 octets, which is 1,024 gibioctets. Its symbol is Tio. It is the binary counterpart of the teraoctet, and at this level the two differ by 10 per cent — the gap that produces the most familiar complaint in consumer computing.
That complaint runs as follows. A drive is sold as one teraoctet, holds exactly one million million octets, and the operating system reports 931 gigaoctets. What it is actually reporting is 0.909 tebioctets, expressed with the wrong label. Nothing is missing from the drive; the number has simply been divided by 1,024 three times and then written with a decimal prefix.
Storage administration lives in this unit. Volume sizes, RAID array capacities, snapshot reserves and quota limits are all quoted in tebioctets by the tools that manage them, because the underlying allocation units are powers of two. A filesystem asked to create a 10-teraoctet volume and one asked to create a 10-tebioctet volume will produce visibly different results.
The difference matters commercially as well as technically. Cloud storage priced per teraoctet and cloud storage priced per tebioctet differ by a tenth in the quantity delivered for the same price, and a contract that does not say which is being used is genuinely ambiguous. Careful procurement documents specify the unit explicitly for exactly this reason.
A tebioctet holds around a quarter of a million photographs, two hundred hours of high-definition video, or the complete text of every book in a large public library many times over. In a household it is more storage than a lifetime of ordinary files will use; in a video production company it is a few days of work.
The correct symbol Tio appears in filesystem tools, in storage array documentation and in standards, and it is worth using even when the audience is unlikely to notice. A figure written with a binary prefix can be converted correctly by anyone who reads it later; one written ambiguously cannot be repaired.
One tebioctet equals 1,099,511,627,776 octets, 1,024 gibioctets, 8 tebibits, or about 1.100 teraoctets.