ISO 2692:2021

Overview

ISO 2692:2021 is an ISO standard in the Geometrical Product Specifications (GPS) family that defines the Maximum Material Requirement (MMR), Least Material Requirement (LMR) and the optional Reciprocity Requirement (RPR) for geometrical tolerancing. This fourth edition clarifies how MMR and LMR apply to linear features of size - specifically cylindrical features and two parallel opposite planes - and provides rules for direct and indirect determination of virtual sizes (MMVS / LMVS). ISO 2692:2021 is part of the GPS system that links dimensional size and geometric deviation to functional performance.

Key topics and requirements

• Scope limitation: MMR, LMR and RPR apply only to features of linear size of cylindrical type or two parallel opposite planes type.
• MMR and LMR concepts: Combine size and geometry control to manage functions such as assemblability (MMR) or minimum wall thickness / material strength (LMR).
• Virtual condition definitions: Specifies maximum material virtual size (MMVS) and least material virtual size (LMVS) and how to determine them indirectly (from feature size + geometric tolerance) or directly (explicit indication).
• Reciprocity Requirement (RPR): Optional modifier that can enlarge permissible size tolerance when the actual geometrical deviation does not fully consume the MMVC/LMVC - useful where functional clearance or material minimums permit greater size variation.
• Datum and multiple-feature rules: Guidance on applying MMR/LMR to datum features, several toleranced features, and simultaneous requirements (SIM).
• Symbols and practice updates: This edition adds direct virtual-size indication, permits SZ/CZ usage for certain cases, and formalizes the SIM modifier for simultaneous tolerance application.

Applications and users

ISO 2692:2021 is practical for design, manufacturing and inspection workflows where size and geometry interact:

• Design engineers: specify MMR/LMR to ensure part assemblability, minimum wall thickness or other function-driven limits.
• Tolerance analysts / GD&T practitioners: combine dimensional and geometric tolerances using MMVS/LMVS and RPR for accurate stack-up analysis.
• Manufacturing & quality control: interpret drawings with MMR/LMR to set inspection criteria and acceptance tests.
• CAD/CAM and metrology teams: implement virtual condition checks and measurement strategies for cylindrical features and paired parallel planes.
  Keywords: ISO 2692:2021, geometrical product specifications, GPS, geometrical tolerancing, MMR, LMR, RPR, virtual condition, assemblability, minimum wall thickness.

Related standards

ISO 2692:2021 links into the GPS framework and references:

• ISO 1101 (geometrical tolerancing - form, orientation, location, run-out)
• ISO 5458, ISO 5459 (patterns, datums)
• ISO 14405-1 (dimensional tolerancing - linear sizes)
• ISO 17450-1 / ISO 17450-3 (GPS general concepts and toleranced features)

Use ISO 2692:2021 when you need a standardized method to control combined size-and-geometry functions (assembly fit, strength, or clearance) for cylindrical and parallel-plane features.