Conversion from Kilooctets to Teraoctets

Information about the Kilooctet (ko)

The kilooctet is a unit of digital information equal to one thousand octets, and therefore to eight thousand bits. Its symbol is ko. It is the smallest of the everyday storage units, and for two decades it was the unit in which the whole capacity of a computer was described.

A kilooctet holds a thousand characters of unaccented text, which is about two hundred words, or a third of a page. The plain-text file of a short letter is a few kilooctets. Almost nothing else in modern computing is this small: an empty document from a word processor is already tens of kilooctets, because the file format carries formatting, fonts and metadata around the text.

The historical importance of the unit is hard to overstate. The Apple II shipped with 4 kilooctets of memory, the Commodore 64 was named for its 64, and the first IBM personal computer could address 640. Programs of real complexity — spreadsheets, word processors, games with graphics and sound — were written to fit inside those numbers, which required a discipline that has largely disappeared.

The kilooctet is also where the decimal and binary confusion began. Memory came in 1,024-octet units because addressing is binary, and everyone called that a kilooctet. Disc manufacturers counted in true thousands. The two conventions differ by 2.4 per cent, which was negligible at this scale, but the same error compounds at each step upward and reaches 10 per cent by the teraoctet.

The IEC resolved the ambiguity in 1998 by defining the kibioctet as 1,024 octets and leaving the kilooctet at exactly 1,000. Operating systems have adopted this unevenly: some report file sizes in true kilooctets, others still divide by 1,024 while writing ko, and a few now write Kio correctly.

Where the unit still appears daily is in network protocols and in the sizes of small resources on the web. A web page's stylesheet, an icon, a certificate, a configuration file, a database index page — all of these are measured in kilooctets, and the standard memory page on most processors is 4 kibioctets, close enough to 4 kilooctets for casual conversation but not for arithmetic.

One kilooctet equals 1,000 octets, 8,000 bits, 8 kilobits, or about 0.9766 kibioctets.

Information about the Teraoctet (To)

The teraoctet is a unit of digital information equal to one million million octets, or a thousand gigaoctets. Its symbol is To. It is the unit of the modern hard drive, and the point at which personal storage stopped being something anyone needed to manage carefully.

A teraoctet holds roughly two hundred and fifty thousand photographs from a phone, or two hundred hours of high-definition video, or a quarter of a million songs. For a person who is not a professional photographer or video editor, a single teraoctet is more storage than a lifetime of ordinary files will fill.

Consumer hard drives crossed one teraoctet in 2007 and now reach twenty or more. Solid-state drives arrived at the same capacities more slowly and at higher cost, but with far greater speed, and the two technologies now divide the market between capacity and performance rather than competing directly.

The teraoctet is where the decimal-binary discrepancy becomes visible enough to annoy. A drive sold as one teraoctet holds a million million octets exactly; the operating system divides by 1,024 four times and reports 0.909 tebioctets, which it usually labels as 931 gigaoctets. The shortfall appears to be 7 per cent, though nothing has actually been lost. At the petaoctet the same arithmetic produces a 12 per cent gap.

Backup and archiving live at this scale. A household's complete collection of photographs, documents and video typically fits in a few teraoctets, which is why external drives are sold in exactly that range. Cloud storage services price in teraoctets too, and the economics of keeping a second copy of everything only work because the unit price of storage has fallen faster than the quantity has grown.

In professional work the teraoctet is a daily quantity rather than a milestone. A day of filming in high resolution produces several teraoctets of raw footage. A genome sequencing run produces a few hundred gigaoctets, so a modest laboratory generates teraoctets a week. Both fields have had to build workflows around moving data that will not fit on any network in reasonable time.

One teraoctet equals 1,000,000,000,000 octets, 1,000 gigaoctets, 8 terabits, or about 0.9095 tebioctets.