ISO 80000-3:2019

Overview

ISO 80000-3:2019, "Quantities and units - Part 3: Space and time", is an international standard that defines names, symbols, definitions and units for quantities related to space and time. The second edition (2019) replaces the 2006 edition with a simplified table of quantities and clearer, more physically precise definitions. Where appropriate, conversion factors are provided. This part of the ISO 80000 series supports consistent use of unit names, symbols and definitions across engineering, science and metrology.

Key topics

The standard systematically lists quantities and their units for space- and time-related measures. Major technical topics include:

• Basic space quantities: length, width, height/altitude, thickness, diameter, radius, distance, path/arc length, position and displacement vectors.
• Geometric measures: area, volume, radius of curvature, curvature, solid and plane angular measures.
• Kinematics and dynamics: velocity (vector and speed), acceleration, angular displacement, angular velocity, angular acceleration.
• Periodic and wave quantities: period, frequency, angular frequency, wavelength, wavenumber (repetency), wave vector, phase angle.
• Wave propagation and damping: phase velocity, group velocity, attenuation, phase coefficient, propagation coefficient, damping and logarithmic decrement.
• Conventions and notation: recommended symbols, sign conventions (e.g., for height and rotational direction) and relationships between quantities (e.g., ω = 2πf).
• Format: a single simplified table (Table 1) giving names, symbols, definitions and units, with explanatory remarks and cross-references to ISO 80000-1 and ISO 80000-2.

Applications and who uses it

ISO 80000-3 is used wherever precise, standardized space-and-time terminology and units are required:

• Metrology and calibration labs - ensure traceability and consistent reporting of length, time and derived measurements.
• Engineers and physicists - harmonize notation in design documents, calculations and technical reports.
• Software developers and data engineers - implement unit libraries, simulation models and data exchange formats that require unambiguous unit semantics.
• Standards writers, technical authors and educators - produce clear documentation, textbooks and training materials using consensus terminology.
• Instrumentation, aerospace, telecommunications and optics - apply standardized wave, frequency and propagation quantities (phase velocity, group velocity, attenuation).

Using ISO 80000-3 helps avoid ambiguity in unit symbols and definitions, improves interoperability of measurement data, and supports regulatory and procurement specifications.

Related standards

• ISO 80000-1 - General principles (International System of Quantities)
• ISO 80000-2 - Mathematics (notation and vectors)
• Other parts of the ISO 80000 and IEC 80000 series for quantities and units across disciplines

Keywords: ISO 80000-3:2019, quantities and units, space and time, unit symbols, metrology, SI units, velocity, frequency, wavelength, attenuation.