ISO/IEC 80000

ISO 80000 or IEC 80000 is an international standard promulgated jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).

The standard introduces the International System of Quantities (ISQ). It is a style guide for the use of physical quantities and units of measurement, formulas involving them, and their corresponding units, in scientific and educational documents for worldwide use. In most countries, the notations used in mathematics and science textbooks at schools and universities follow closely the guidelines in this standard.

The ISO/IEC 80000 family of standards was completed with the publication of Part 1 in November 2009.[1]


The standard has 14 parts.[2]


ISO 80000-4:2006 supersedes ISO 31-3.[3] and specifies names and symbols for quantities and units of classical mechanics, and defines these names and symbols. The document is under review.[4]


ISO 80000-5:2007 supersedes ISO 31-4[5] which "gives names, symbols and definitions for quantities and units of thermodynamics". The document is under review.[6]


IEC 80000-6:2008 supersedes ISO 31-5[7] as well as IEC 60027-1, and specifies names and symbols for quantities and units related to electromagnetism, and defines these quantities and units.


ISO 80000-7:2008 supersedes ISO 31-6,[8] and specifies names and symbols to quantities and units for light and other electromagnetic radiation, and defines these quantities and units. The document is under review.[9]


ISO 80000-8:2007 specifies names, symbols for quantities and units of acoustics and provides definitions for these quantities and units. It supersedes ISO 31-7[10] and is under review.[11] It has a foreword; introduction; scope; normative references; and names, symbols and definitions. The standard includes definitions of sound pressure, sound power and sound exposure, and their corresponding levels: sound pressure level, sound power level and sound exposure level. For example:

Information science and technology

IEC 80000-13:2008 defines quantities and units used in information science, and specifies names and symbols for these quantities and units.[12] The document was last-published in 2008, and replaces subclauses 3.8 and 3.9 of IEC 60027-2:2005 and IEC 60027-3. It has a scope; normative references; names, definitions and symbols; and prefixes for binary multiples. Quantities defined in this standard are:

The Standard also includes definitions for units relating to information technology, such as the erlang (symbol E), bit (bit), octet (o), byte (B), baud (Bd), shannon (Sh), hartley (Hart) and the natural unit of information (nat).

Clause 4 of the Standard defines standard binary prefixes used to denote powers of 1024 as 10241 (kibi-), 10242 (mebi-), 10243 (gibi-), 10244 (tebi-), 10245 (pebi-), 10246 (exbi-), 10247 (zebi-) and 10248 (yobi-).

Other areas

Part Year Name Replaces Status[13]
ISO 80000-1[14] 2009 General ISO 31-0, IEC 60027-1 and IEC 60027-3 under review
ISO 80000-2[15] 2009 Mathematical signs and symbols to be used in the natural sciences and technology ISO 31-11, IEC 60027-1 under review
ISO 80000-3[16] 2006 Space and time ISO 31-1 and ISO 31-2 under review
ISO 80000-9 2008 Physical chemistry and molecular physics ISO 31-8 under review
ISO 80000-10 2009 Atomic and nuclear physics ISO 31-9 and ISO 31-10 under review
ISO 80000-11 2008 Characteristic numbers ISO 31-12 under review
ISO 80000-12 2009 Solid state physics ISO 31-13 under review
IEC 80000-14 2008 Telebiometrics related to human physiology IEC 60027-7

International System of Quantities

Part 1 of ISO/IEC 80000 introduces the International System of Quantities and describes its relationship with the International System of Units (SI). Specifically, its introduction states "The system of quantities, including the relations among the quantities used as the basis of the units of the SI, is named the International System of Quantities, denoted 'ISQ', in all languages.", and further clarifies that "ISQ is simply a convenient notation to assign to the essentially infinite and continually evolving and expanding system of quantities and equations on which all of modern science and technology rests".

Units of ISO/IEC 80000

The standard includes all SI units but is not limited to only SI units. Units that form part of the standard but not the SI include the units of information storage (bit and byte), units of entropy (shannon, natural unit of information and hartley), the erlang (a unit of traffic intensity) and units of level (neper and decibel). The standard includes all SI prefixes as well as the binary prefixes kibi-, mebi-, gibi-, etc., originally introduced by the International Electrotechnical Commission to standardise binary multiples of byte such as mebibyte (MiB), for 10242 bytes, to distinguish them from their decimal counterparts such as megabyte (MB), for precisely one million (10002) bytes. In the standard, the application of the binary prefixes is not limited to units of information storage. For example, a frequency ten octaves above one hertz, i.e., 210 Hz (1024 Hz), is one kibihertz (1 KiHz).

Historically, these binary prefixes were standardized first in a 1999 addendum to IEC 60027-2. The harmonized IEC 80000-13:2008 standard obsoletes and replaces subclauses 3.8 and 3.9 of IEC 60027-2:2005, which had defined the prefixes for binary multiples. The only significant change in IEC 80000 is the addition of explicit definitions for some quantities.

See also


External links

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