Terabyte

Terabyte (TB), equivalent to 10¹² (1 000 000 000 000 —one trillion—) bytes.

Do not confuse with:

Tebibyte (TiB), equivalent to 2⁴⁰ (1 099 511 627 776 —more than a billion—) bytes.

Related equivalencies:

1 TB = 10³ GB = 10⁶ MB = 10⁹ kB = 10¹² bytes.

1 YB = 10³ ZB = 10⁶ EB = 10⁹ PB = 10¹² TB.

History

It is a unit of information adopted in 1960. The prefix tera- comes from the Greek τέρας, meaning "monster" or "beast".

Multiple of 1000 or 1024?

1000 = 10³ (power of 10, base decimal).

1024 = 2¹⁰ (power of 2, binary base).

• During computer startups, computers were designed, operated and programmed in binary base almost without exception. Given this, the units to measure their capabilities were also expressed in binary base, as multiples of 1024.

• In naming these multiples, they took the prefixes, as kilo- or tera-of the International System of Units (IS), defined to express decimal base quantities. This generated confusion between the use of 1000 and 1024.

Thus, for example, the prefix kilo- it ended up meaning different values according to the basis that it was understood. When measuring central memory units, it was normal to say that kilobyte it was 1024 bytes, because the implicit base was binary. However, when measuring disk storage space, it was understood that a kilobyte it was equivalent to “only” 1000 bytes, because the implicit base was decimal.

• In order to clarify this confusion and accentuate the difference between the implicit decimal and binary bases, the International Electrotechnical Commission, in 1998 defined new prefixes for the multiples expressed as powers of 2, that is, in binary basis. These new prefixes were generated by combining those of the International System with the word binary (binary, in English, see binary prefix), for example kibi- or tebi-.

• This way, terabyte is reserved exclusively to refer to the amount of 10¹² bytesAccording to the prefix tera of the YES — Note 10¹² is expressed in base 10 (decimal)—. Instead, to refer to amounts on base 2 (binary) it is no longer correct to use the prefix tera- the new prefix is to be used tebi- (combination of tera and binary), which gives rise to the term tebibyteequivalent to the amount of 2⁴⁰ bytes.

This new nomenclature has not yet been widely adopted by the computing community, but it has been by most storage device manufacturers.