Overview
ISO 1101:2017 - Geometrical product specifications (GPS) - Geometrical tolerancing - Tolerances of form, orientation, location and run-out - defines the graphical symbol language and interpretation rules used to specify geometric requirements on engineering drawings and models. The standard provides the foundation for geometrical tolerancing, showing how to indicate tolerances of form, orientation, location and run‑out with visible annotation (including Theoretically Exact Dimensions (TEDs)) or indirectly by attaching specifications to a 3D CAD model (per ISO 16792).
Key topics and requirements
ISO 1101:2017 organizes the geometrical tolerancing system and covers:
- Symbols and tolerance frame - standardized symbol language for form, orientation, location and run‑out characteristics and how to build the tolerance indicator.
- Toleranced features & tolerance zones - rules for defining tolerance zones (defaults, variable width, cylindrical and spherical zones).
- Datum and datum systems - how to indicate datum features, datum section rules, and datum-related specifications.
- Geometrical characteristic definitions - straightness, flatness, roundness, cylindricity, line & surface profile, parallelism, perpendicularity, angularity, position, concentricity/coaxiality, symmetry, circular and total run‑out.
- Special topics - stacked tolerances, restrictive specifications, projected toleranced features, moveable assemblies, intersection/orientation/collection planes, direction features and graphical language conventions.
- Theoretically Exact Dimensions (TEDs) - illustration and use in visible annotation.
- References to additional international standards (Clause 2, Tables 3 & 4) for more detailed tolerancing guidance.
Practical applications
ISO 1101:2017 is essential for:
- Creating unambiguous engineering drawings and 3D CAD annotations with consistent geometric requirements.
- Defining inspection criteria and measurement procedures for manufacturing and metrology.
- Specifying tolerance zones used in tolerance stack-ups, GD&T planning and quality control.
- Communicating design intent across supply chains - from design and manufacturing to inspection and procurement.
Who should use this standard
- Mechanical and design engineers drafting parts and assemblies
- Metrologists and quality engineers developing inspection plans
- CAM programmers and manufacturing engineers responsible for producibility
- CAD specialists applying model-based definition (MBD) and ISO 16792 workflows
- Technical trainers and standards committees implementing GPS/GD&T practices
Related standards
ISO 1101:2017 is part of the GPS suite and is commonly used with:
- ISO 16792 (CAD practices for MBD)
- Other ISO GPS documents referenced in Clause 2 and tables of ISO 1101 for detailed characteristic definitions and measurement methods
Using ISO 1101:2017 ensures consistent, internationally recognized geometrical tolerancing language for clearer specifications, better interchange of CAD/technical data, and improved manufacturability and inspection.