TC 25 - Quantities and units

IEC 80000-13:2025 specifies names, symbols and definitions for quantities and units used in information science and technology. Where appropriate, conversion factors are also given. Prefixes for binary multiples are also given. International Standard IEC 80000-13 has been prepared by IEC technical committee 25: Quantities and units in close cooperation with ISO/TC 12: Quantities and units.
This second edition cancels and replaces the first edition published in 2008. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
addition of new prefixes for binary multiples.

ISO 80000-1:2022 This document gives general information and definitions concerning quantities, systems of quantities, units, quantity and unit symbols, and coherent unit systems, especially the International System of Quantities (ISQ).
The principles laid down in this document are intended for general use within the various fields of science and technology, and as an introduction to other parts of this International Standard.
The ISO/IEC 80000 series does not, as yet, cover ordinal quantities and nominal properties.

IEC 80000-6:2022 gives names, symbols, and definitions for quantities and units of electromagnetism. Where appropriate, conversion factors are also given. International Standard IEC 80000-6 has been prepared by IEC technical committee 25: Quantities and units, and their letter symbols in close cooperation with ISO/TC 12, Quantities and units.
This standard is based on classical electromagnetism, i.e. mainly Maxwell’s equations. No reference is made to quantum field theories.
IEC 80000-6:2022 cancels and replaces the first edition published in 2008. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
1) With the new definitions in SI, some previously exact values for quantities now must be determined experimentally while other quantities are given as exact values;
2) Item 6-2.2, elementary charge added;
3) Item 6-11.4, induced voltage, added;
4) Index of entries added;
5) Editorial alignment to other parts of the IEC and ISO 80000 series.

This document gives names, symbols, definitions and units for quantities of acoustics. Where appropriate, conversion factors are also given.

ISO 80000-3:2019 gives names, symbols, definitions and units for quantities of space and time. Where appropriate, conversion factors are also given.

ISO 80000-11:2019 gives names, symbols and definitions for characteristic numbers used in the description of transport and transfer phenomena.

This document gives names, symbols, definitions and units for quantities of thermodynamics. Where appropriate, conversion factors are also given.

This document gives names, symbols, definitions and units for quantities of mechanics. Where appropriate, conversion factors are also given.

This document gives names, symbols, definitions and units for quantities used in atomic and nuclear physics. Where appropriate, conversion factors are also given.

This document gives names, symbols, definitions and units for quantities of physical chemistry and molecular physics. Where appropriate, conversion factors are also given.

This document gives names, symbols, definitions and units for quantities used for light and optical radiation in the wavelength range of approximately 1 nm to 1 mm. Where appropriate, conversion factors are also given.

This document specifies mathematical symbols, explains their meanings, and gives verbal equivalents and applications.
This document is intended mainly for use in the natural sciences and technology, but also applies to other areas where mathematics is used.

This document gives names, symbols, definitions and units for quantities of condensed matter physics. Where appropriate, conversion factors are also given.

IEC 60027-2:2019 is applicable to telecommunications and electronics. It gives names and symbols for quantities and their units.

IEC 60375:2018 specifies the rules for signs and reference directions and reference polarities for electric currents and voltages in electric networks.

Defines ways for new microprocessor systems to perform binary floating point arithmetic in software, in hardware or in any combination of hardware and software.[
]Note: -For the price of this publication, please consult the ISO/IEC price-code list.

IEC 60027-7:2010 is applicable to generation, transmission, and distribution of electric energy. It gives names and letter symbols for quantities and units. In addition, rules for multiple subscripts and their succession are given. It is an addition to IEC 60027-1. Therefore letter symbols already given in IEC 60027-1 are repeated only if they have a special meaning in the field of power generation, transmission, and distribution or if they are used in this field with special subscripts.

ISO 80000-2:2009 gives general information about mathematical signs and symbols, their meanings, verbal equivalents and applications. The recommendations in ISO 80000-2:2009 are intended mainly for use in the natural sciences and technology, but also apply to other areas where mathematics is used.

ISO 80000-10:2009 gives the names, symbols, and definitions for quantities and units used in atomic and nuclear physics. Where appropriate, conversion factors are also given.

ISO 80000-1:2009 gives general information and definitions concerning quantities, systems of quantities, units, quantity and unit symbols, and coherent unit systems, especially the International System of Quantities, ISQ, and the International System of Units, SI. The principles laid down in ISO 80000-1:2009 are intended for general use within the various fields of science and technology and as an introduction to other parts of the Quantities and units series. Ordinal quantities and nominal properties are outside the scope of ISO 80000-1:2009.

ISO 80000-12:2009 gives names, symbols and definitions for quantities and units of solid state physics. Where appropriate, conversion factors are also given.

ISO 80000-9:2009 gives names, symbols, and definitions for quantities and units of physical chemistry and molecular physics. Where appropriate, conversion factors are also given.

ISO 80000-11:2008 gives the names, symbols and definitions for characteristic numbers used in the description of transport phenomena.

ISO 80000-7:2008 gives names, symbols and definitions for quantities and units for light and other electromagnetic radiation. Where appropriate, conversion factors are also given.

IEC 62428:2008 deals with transformations from original quantities into modal quantities for the widely used three-phase a.c. systems in the field of electric power engineering. The examination of operating conditions and transient phenomena in three-phase a.c. systems becomes more difficult by the resistive, inductive or capacitive coupling between the phase elements and line conductors. Calculation and description of these phenomena in three-phase a.c. systems are easier if the quantities of the coupled phase elements and line conductors are transformed into modal quantities. The calculation becomes very easy if the transformation leads to decoupled modal systems. The original impedance and admittance matrices are transformed to modal impedance and admittance matrices. In the case of decoupling of the modal quantities, the modal impedance and admittance matrices become diagonal matrices.

In IEC 80000-6:2008, names, symbols, and definitions for quantities and units of electromagnetism are given. Where appropriate, conversion factors are also given. International Standard IEC 80000-6 has been prepared by IEC technical committee 25: Quantities and units, and their letter symbols in close cooperation with ISO/TC 12, Quantities, units, symbols, conversion factors. This first edition of IEC 80000-6 cancels and replaces the second edition of ISO 31-5, published in 1992, and its amendment 1 (1998).

In IEC 80000-13:2008, names, symbols and definitions for quantities and units used in information science and technology are given. Where appropriate, conversion factors are also given. International Standard IEC 80000-13 has been prepared by IEC technical committee 25: Quantities and units, and their letter symbols in co-operation with ISO/TC 12. This standard cancels and replaces subclauses 3.8 and 3.9 of IEC 60027-2:2005. The only significant change is the addition of explicit definitions for some quantities.

ISO 80000-8:2007 gives names, symbols and definitions for quantities and units of acoustics. Where appropriate, conversion factors are also given.

ISO 80000-5:2007 gives names, symbols and definitions for quantities and units of thermodynamics. Where appropriate, conversion factors are also given.

This part of IEC 60027 is applicable to control technology. It gives names and symbols for quantities, signals and functions, and their units.

This part of IEC 60027 is applicable to rotating electric machines. It gives names and symbols for quantities and units.

ISO 80000-4:2006 specifies the names, symbols and definitions for quantities and units of classical mechanics. Where appropriate, conversion factors are also given.

ISO 80000-3:2006 gives names, symbols and definitions for quantities and units of space and time. Where appropriate, conversion factors are also given.

Defines rules for the use and writing of letter symbols for telecommunications and electronics.

Lays down rules for signs and reference directions and reference polarities for electric currents and voltages in electric networks, as well as for the corresponding quantities in magnetic circuits.

Applies to logarithmic quantities and units. Quantities that can be expressed as the logarithm of a dimensionless quantity, such as the ratio of two physical quantities of the same kind, can be regarded and treated in different ways. In many cases, differences do not affect practical treatment.

Defines rules for the use and writing of symbols for general quantities, symbols for quantities concerning two-port networks, symbols for line transmissions of signals (including cables), symbols for radio wave propagation, symbols for quantities concerning waveguide propagation, symbols for aerials (antennas), symbols for electro-acoustics and symbols for equivalent circuits of piezo-electric crystals.

Specifies procedures for applying and preparing compliance test plans for success ratio or failure ratio. The procedures are based on the assumption that each trial is statistically independent. Supersedes IEC 605-5 and its amendment 1.

Should be used in conjunction with IEC 61120-1 and IEC 61120-3.

Defines the use of the DAT logo on DAT equipment and accessories. Provides information on the specification, copyright and application of the logo.

Applies to calibration tapes for assessing and correcting the technical performance of equipment for DAT cassette systems.

Corrected and reprinted 1995-03-31.
The contents of the corrigendum of April 1993 have been included in this copy.

In IEC 80000-14:2008, names, symbols, and definitions for quantities and units of telebiometrics related to human physiology are given. This part of IEC 80000 encompasses quantities and units for physiological, biological or behavioural characteristics that might provide input or output to telebiometric identification or verification systems (recognition systems), including any known detection or safety thresholds. It also includes quantities and units concerned with effects on a human being caused by the use of a telebiometric device. International Standard IEC 80000-14 has been prepared by IEC technical committee 25: Quantities and units, and their letter symbols in co-operation with ISO/TC 12.

Applies to control technology. Gives names and symbols for quantities, signals and functions and their units. Replaces IEC 60027-2, section 11.