Byte

From Reboil


A byte is a unit of measurement for quantifying amounts of data.

Stats

Multiple-byte units

Units based on powers of 10

kilobyte
(a.k.a. KB) 103 = 1,000 bytes.
megabyte
(a.k.a. MB) 106 = 1,000,000 bytes.
gigabyte
(a.k.a. GB) 109 = 1,000,000,000 bytes.
terabyte
(a.k.a. TB) 1012 = 1,000,000,000,000 bytes.
petabyte
(a.k.a. PB) 1015 = 1,000,000,000,000,000 bytes.
exabyte
(a.k.a. EB) 1018 = 1,000,000,000,000,000,000 bytes.

Units based on powers of 2

The following unit names were first approved by IEC in 1998-12 and published in 1999-01 under Amendment 2 to IEC International Standard IEC 60027-2: Letter symbols to be used in electrical technology - Part 2: Telecommunications and electronics. The amendment was incorporated into the second edition of IEC 60027-2 published on 2000-11. [1]

kibibyte
(a.k.a. KiB) 210 = 1,024 bytes.
mebibyte
(a.k.a. MiB) 220 = 1,048,576 bytes.
gibibyte
(a.k.a. GiB) 230 = 1,073,741,824 bytes.
tebibyte
(a.k.a. TiB) 240 = 1,099,511,627,776 bytes.
pebibyte
(a.k.a. PiB) 250 = 1,125,899,906,842,624 bytes.
exbibyte
(a.k.a. EiB) 260 = 1,152,921,504,606,846,976 bytes.

Notable violators

Amazon S3
The S3 console defines 1 GB = 230 bytes.[2]
Microsoft Windows
File Explorer defines 1 KB = 210 bytes.
PHP
PHP defines 1 kilobyte, 1 k, and 1 K to equal 1024 bytes (210 bytes).[3]

History

  • 2000-11-22: IEC publishes the second edition of IEC 60027-2: Letter symbols to be used in electrical technology - Part 2: Telecommunications and electronics which incorporates a 1999-12 ammendment recommending the “kibibyte”/”KiB”, etc. binary prefix convention.[4]

Baltakatei history

  • 2023-06-13: I discovered that the php language uses a notation that violates SI and IEC conventions, asserting that 1K means 1024 bytes.
  • 2023-07-02: I found a NIST web page containing citations describing the 1998 origin of the IEC recommendation for prefixes for binary multiples.[1]

See also

External links

References

  1. ↑ 1.0 1.1 “Prefixes for binary multiples”. (n.d.). The NIST Reference on Constants, Units, and Uncertainty. Accessed 2023-07-02. Archived from the original on 1999-10-01. “…the name of each new prefix is derived from the name of the corresponding SI prefix by retaining the first two letters of the name of the SI prefix and adding the letters "bi," which recalls the word "binary." Similarly, the symbol of each new prefix is derived from the symbol of the corresponding SI prefix by adding the letter "i," which again recalls the word "binary." ”.
  2. ↑ “Amazon S3 pricing”. (n.d.). Amazon Web Services. Accessed 2023-07-02. Archived from the original on 2023-06-16. “Amazon S3 storage usage is calculated in binary gigabytes (GB), where 1 GB is 230 bytes. This unit of measurement is also known as a gibibyte (GiB), defined by the International Electrotechnical Commission (IEC). Similarly, 1 TB is 240 bytes, i.e. 1024 GBs.”.
  3. ↑ “Using PHP”. (n.d.). php.net. Accessed 2023-06-13. “Note: kilobyte versus kibibyte. The PHP notation describes one kilobyte as equalling [sic] 1024 bytes, whereas the IEC standard considers this to be a kibibyte instead. Summary: k and K = 1024 bytes.”.
  4. ↑ “Letter symbols to be used in electrical technology - Part 2: Telecommunications and electronics”. (2000-11-22). IEC Webstore. Accessed 2023-07-02. Archived from the original on 2016-04-29.
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