Materials, geometry and pressure
ISO 1101: Geometrical product specifications (GPS), geometrical tolerancing
The language of geometrical tolerances on ISO drawings.
Reference noteThis page is an independent plain-language summary written by QUALITAS TR. It does not reproduce the standard. Always work from the current official edition, available from ISO, the International Organization for Standardization, and national standards bodies such as TSE in Turkey (official page). QUALITAS TR supports organisations against this standard; it does not certify them.
01Purpose
ISO 1101 defines the symbolic language and rules for specifying geometrical tolerances of form, orientation, location and run-out on technical drawings.
02Scope
Part of the ISO GPS system together with ISO 5459 (datums), ISO 2692 (material requirements) and ISO 8015 (fundamental principles). ASME Y14.5 is a different, though similar, system.
03Main requirements
- Tolerance characteristics: straightness, flatness, roundness, cylindricity, profile, parallelism, perpendicularity, angularity, position, concentricity, symmetry, run-out
- Tolerance frame structure and tolerance zones
- Reference to datums and datum systems
- Modifiers and specification elements
04Typical applications and industries
All machined and fabricated parts drawn to ISO standards. See dimensional inspection.
05Audit and inspection considerations
- Is the drawing ISO or ASME based?
- Are datums established as intended in measurement?
- Is the principle of independency (ISO 8015) understood?
06Common nonconformities
- Datum set-up differs between supplier and buyer
- Position evaluated without datum reference frame
- ASME interpretation applied to ISO drawing
07How QUALITAS TR can support
Our engineers interpret GD&T in drawing reviews and first article inspections.