Overview
EN ISO 80000-4:2019/A1:2025 is an amendment to Part 4 of the ISO 80000 series, which defines quantities and units for mechanics. Published and adopted by CEN in 2025, this amendment updates normative references and clarifies how names, symbols, definitions and units for mechanical quantities are specified with reference to the International System of Units (SI).
Key topics and requirements
- Reference to SI (BIPM): The amendment explicitly refers to the International System of Units (SI), 9th edition (2019) published by BIPM as a normative reference. This anchors mechanical quantities to the current SI definitions and rules.
- Clarified clause on terms and definitions: Clause 3 is revised so that names, symbols, definitions and units for quantities used in mechanics are given in Table 1 and in the SI. This strengthens the link between the standard’s tabulated quantities and SI conventions.
- Formal adoption and status: The document is an official CEN amendment (approved by CEN) and is to be implemented as a national standard by CEN members, ensuring harmonized use across participating countries.
- Scope alignment: The amendment supplements EN ISO 80000-4:2019 without modifying the core standard’s content, providing targeted editorial and normative updates.
Applications and users
This amendment supports consistent use of units, symbols and definitions in any context where mechanics quantities are recorded, exchanged or interpreted:
- Engineers and designers ensuring consistent unit usage across calculations, drawings and specifications.
- Metrologists and calibration laboratories aligning measurements with SI definitions and international practice.
- Standards developers and technical committees harmonizing cross‑discipline documents that reference mechanical quantities.
- Software developers and simulation tool vendors implementing unit-aware systems, libraries or CAD/CAE models.
- Educators and technical authors producing textbooks, guides and documentation that must follow standardized terminology.
Benefits
- Improves interoperability of technical data and documentation across industries and borders.
- Reduces ambiguity in units and symbols used in mechanics by explicitly tying them to the SI.
- Facilitates regulatory and procurement compliance where standardized measurement terminology is required.
Related standards
- ISO 80000 series (other parts defining quantities and units for physics, electromagnetism, thermodynamics, etc.)
- BIPM - The International System of Units (SI), 9th edition (2019)
For implementers, consult your national standards body for the official text, implementation timeline and any national endorsements of EN ISO 80000-4:2019/A1:2025.