Dimensional and Geometric Tolerancing (ISO GPS)

Basic course - Online (English)

Reduce product costs, increase the value of your products and minimise product liability by applying dimensional and geometric tolerances in compliance with functional, manufacturing, and testing requirements and based on current GPS standards of the ISO (ISO GPS)

The concept behind our training – and how you benefit

Our online fundamentals course on dimensional and geometric tolerancing (ISO GPS) covers 6 key topics divided into 5 modules. Each module lasts 3.5 hours (3.25 hours of actual instruction with a 15-minute break as required). Modules usually take place two or three times per week. Arranging the course as separate modules allows you to reflect on and ‘assimilate’ the topics addressed in each module. Admittedly, some of the more detailed topics may require contemplation while away from the course.

To make the course more effective, the online ISO GPS fundamentals course (which can be viewed between modules) offers you the opportunity to work on example exercises, which also match course content. To kick off each subsequent module, in addition to reviewing previous topics there is an open discussion among the course participants of the exercise examples and any questions you may have.

In a similar way to actual face-to-face courses, you may ask questions at any time during the course (via video or the chat function). You can also contact the presenter or other participants. As a result, we have limited the maximum number of participants to 15. If you are unable to attend a module, you can catch up at the next possible date (naturally, free of charge).

You will also receive detailed materials when you register for the online course. Documentation is updated to reflect the latest status of standards and includes a variety of examples of actual practice and applications. All materials have been designed to be used as a reference manual after the course.


Unambiguous and complete product specifications are fundamentally impossible without geometric tolerancing. Most product specifications are still based on tolerances that allow products to be manufactured which don’t even fulfill functional requirements properly.

With quality requirements intensifying, an increasing number of tasks being shared, and the need to reduce product costs, product specifications should not only be unambiguous and complete, they should also provide proper descriptions of functional requirements. Sadly, one aspect that is often overlooked is the need to ensure tolerancing conforms to current standards.

Furthermore, many companies only actually realize that the tolerancing methods applied within their product specifications fall short of the mark when their third-party suppliers or international customers enter the scene. More often than not, incorrect or functionally unsuitable tolerancing wastes valuable time, results in expensive production processes, and makes testing difficult and cost-intensive. On top of that, it requires intensive coordination and clarification between different specialists working in design, production, and quality assurance. Despite this, the outcome is not always improved product quality.

In the case of third-party manufacturing, technical product specifications constitute legally binding contractual documents, so if they are incomplete, contain ambiguities, or even overlook crucial tolerancing rules, they present a major risk when it comes to product liability.

Dimensional and geometric tolerancing based on the current GPS standards of the ISO represent an extraordinarily multifaceted and complex field. These days tolerancing spans a whole host of individual standards, 151 of which have already been published and 23 of which are still being prepared. Few companies have given sufficient consideration to introducing tolerance management in such a way that it complies with functional, manufacturing, and testing requirements. As a result, it is becoming increasingly difficult to develop products and manufacture in a global environment; when you do so you have to invest a great deal of time and effort in coordination. Furthermore, it is becoming impossible to transition to model-based product definition (i.e. completely digital and thus machine-readable product documentation) without applying the ISO GPS rules.

Many companies only become aware of the inadequacy of the tolerancing methods they apply to engineering drawings (product specifications) when their mostly international third-party suppliers enter the scene, an increasing number of quality problems arise, or more time and money have to be invested in coordination.

Design engineers and other members of staff in production and quality assurance are often overwhelmed when it comes to the correct (i.e. functionally appropriate) application and interpretation of available normative tools, as laid down in the GPS standards of the ISO (ISO GPS). It is also still not widely known that there have been extensive changes in the field of dimensional and geometric tolerancing in recent years, with new fundamental standards, rules, and principles added. If engineering, development, production, and quality assurance fail to implement international standards (ISO GPS) rigorously, in the medium term this can place companies at a significant competitive disadvantage.

Given that roughly 70% of the costs of technical products are accounted for by design and development, it is clear that consistently applying the diverse normative tools of ISO GPS standards can not only significantly improve product quality, but also result in substantial reductions in manufacturing and inspection costs (tolerances are hidden cost drivers). In addition, standard-compliant and function-compliant tolerancing empowers companies to measurably improve understanding between engineering and development, production, quality assurance, procurement, sales, suppliers, and customers – worldwide.

Course objectives

This course will provide you with the most important tools available today for creating engineering drawings in compliance with current standards. These tools are particularly important for geometric tolerancing in compliance with the functional, manufacturing, and inspection requirements based on the latest international standards laid down under the ISO GPS system. The course also looks at practical approaches, especially for describing functional requirements. Your instructor will introduce you to this complex topic step by step. Particular emphasis is placed on explaining complex topics in a clear manner. To dig deeper into the topics, use is made of case studies which are closely based on business practice, also showing how functional requirement can be described. Course participants will be made familiar with the latest standardization trends, which without exception are international. They are also provided with practical ideas for implementing what they learn in their everyday engineering work.

Benefits - what you will learn in the course

  • The most important principles of tolerancing, how to apply tolerancing in practice, and the fundamental rules of the ISO GPS system of standards (e.g. ISO 8015, ISO 17450-1 bis 3).
  • The impact of non-standard, ambiguous tolerancing on manufacturing and inspection costs, including impacts on functionality and product liability.
  • The correct use of the most important tools of geometric tolerancing. This will put you in a position to select the optimal tolerancing strategy with regard to functional requirements as well as manufacturing and inspection costs. You will also be able to transfer acquired knowledge to technical product documentation (e.g. engineering drawings) in compliance with current tolerancing standards.
  • How to identify and reliably eliminate incorrect, ambiguous, and misleading dimensional and geometric tolerancing used in previous technical product specification. In addition to reducing production and inspection costs, this also enhances the functionality and thus the value of products. Furthermore, since engineering drawings are legally binding contractual documents, this course can play a decisive role in avoiding potential legal disputes with your customers or suppliers.
  • The most important tools of cost reduction (including avoiding over-cautious tolerancing or specifying unusable datums and datum systems). This enables you to identify potential savings without affecting the functionality of your products.
  • An understanding of the main changes that have occurred in recent years in the field of dimensional and geometric tolerancing, especially due to the introduction of the ISO GPS system of standards. Discussion will be given to the impact of these changes.
  • How to define datums and datum systems in keeping with functional, manufacturing, and inspection requirements in order to pave the way for profitable production and unambiguous inspection of products.
  • Procedural rules applying to digital product definition, the integration of digital CAD data sets, and the correct definition of general dimensional and geometric specifications.
  • The most important default rules (rules and principles that do not need to be agreed separately).
  • The practical application of all aspects of dimensional and geometric tolerancing on a large number of examples.

All participants will get an exclusive Login to the customer area of our Website with numerous valuable and current informations, helpful hints and practical examples.

Course contents

Topic 1: Structure of the ISO GPS system of standards, fundamental concepts and principles (ISO 8015:2011)

Law, product liability and implications

  • Product liability: consequences of incorrect, ambiguous specifications not complying with current standards - who is liable in the event of damage?  
  • Overview of the most frequent tolerancing faults contained in mechanical engineering drawings and their consequences
  • Cost effectiveness of tolerances and collaboration within the company

The ISO GPS body of standards - stucture, purpose and benefits

  • Geometric product specification (GPS) - the GPS matrix model  (ISO 14638:2015)
  • The role of the ISO GPS system of standards as an essential requirement for using model-based definition (MBD) 
  • Types of documents with GPS (ISO/TS 21619)
  • Operator concept and specification operators (ISO 17450-2:2013)

Digital product definition and 3D visualisation 

  • Product documentation without technical drwaings (VDA 4953-2:2015)
  • Digital product definition data practices (ISO 16792:2021)

Fundamental concepts, principles and rules acc. to  ISO 8015:2011

  • Relevance of fundamental principles, explained by typical examples 
    - Invocation principle
    - Principle of GPS standard hierarchy
    - Definitive drawing principle
    - Feature principle
    - Independency principle
    - Decimal principle
    - Default principle
    - Reference condition principle
    - Rigid workpiece principle
    - Duality principle
    - Grundsatzes der Dualität
    - Functional control principle
    - General specification principle
    - Responsibility principle
  • Impact of ISO 8015:2011 on existing and new product specifications (correct interpretation)
Topic 2: Dimensional tolerancing – applicability and limitations
  • Erroneous dimensional tolerancing within technical product documentation (examples) and its impact on function
  • Two-point size as a default ISO specification operator for linear size (ISO 14405-1:2016 and ISO 17450-3:2016) – impact on component function and verification possibilities
  • The envelope requirement as a drawing-specific specification operator for linear size (`envelope principle´): impact on function, manufacturing and inspection costs
  • Determination of a reasonable drawing-specific or company-specific GPS specification operator in light of available inspection equipment
  • Describing functional requirements by making correct choices and correctly determining specification modifiers for linear size (ISO 14405-1:2016), e.g. minimum circumscribed size or envelope requirement
  • ISO code system for tolerances on linear sizes (ISO 286-1:2010, -2:2010): correct interpretation of ISO coded linear sizes (e.g. 30 H7) 
Topic 3: Basics of geometrical tolerancing, form specifications

Basics of geometrical tolerancing

  • Erroneous geometric tolerancing within technical product documentation (examples) and its impact on the function
  • Indication of restricted toleranced features
  • Theoretically exact dimension (TED) and theoretically exact feature (TEF)

Tolerance zones

  • Tolerance indicator - structure and rules for the indication of integral and derived features. possibilities for alternative indication of derived features
  • Tolerance zones - shape (e.g. linear, circular, spherical) and witdh; examples of application
  • Offset tolerance zone with specified offset (UZ modifier) and offset tolerance zone with unspecified offset (OZ modifier) 

Form specifications

  • Straightness specification of edges, central lines and the line elements of cylinders
  • Flatness specification for integral and derived features
  • Roundness specification for cylindrical surfaces and spheres; direction feature indicator
  • Cylindricity specification
  • Line and surface profile specifiaction not related to a datum (ISO 1660:2017)
  • Typical use cases for tolerances of form (e.g. sealing surfaces)
  • Reference features: defaults (ISO 12180-1, -2; ISO 12181-1, -2 ISO 12780-1, -2; ISO 12781-1, -2), modifiers for association of reference features, identification of possible contradictions
  • Recognising incomplete or erroneous inspection reports 
Topic 4: Datums and datum systems (ISO 5459:2011)
  • The role of datums, specifying datums to fulfil functional requirements, typical cases of application and tips
  • Datum feature indicator, rules for the indicaton of integral and derived features
  • Direct and indirect geometric tolerancing of datum features
  • Default rules for establishing single datums acc. to ISO 5459: plane, circle and cylinder, sphere, two parallel lines, and two parallel planes, cone and wedge
  • Common datum: drawing indication and rules for establishing common datums, examples of applications, establishing a common datum from a collection of two or more surfaces, possible verification problems
  • Datum systems: structure and interpretation, typical application cases and tips
  • Identification of useless datums and datum systems; remedies
  • Datum targets: symbolism, fixed and moveable datum targets, contacting feature [CF]
  • Exercises and practical examples of establishing datums with regard to functional requirements, manufacturing and inspection
Topic 5: Tolerances of orientation, location and run-out (ISO 1101:2017)

Fundamental priciples and mathematics

  • Fundamental principles of describing functional requirements by constraining and releasing degrees of freedom
  • Situation features and symmetry classes of surfaces

Tolerances of orientation

  • Application rules, examples and limits (ISO 1101:2017)
  • Parallelism specification
  • Perpendicularity specification
  • Angularity specification
  • Line and surface profile (orientation specification; ISO 1660:2017)

Tolerances of location

  • Fundamental rules, examples and differences between tolerances of orientation and location
  • Position specification
  • Coaxiality and concentricity specification
  • Symmetry specification
  • Line and surface profile specification (location specification; ISO 1660:2017)

Circular run-out and total run-out specification

  • Application rules, examples and limits
  • Circular run-out specification (radial, axial, in any direction, in a specified direction) 
  • Total run-out (radial and axial)
  • Difference between circular run-out (radial), roundness and coaxiality; pracitcal examples
Topic 6: General geometric specifications, non-rigid parts and projected tolerance zone

General dimensional and geometric specifications

  • Ambiguities and errors of ISO 2768-1, -2 (withdrawn) and ISO 20457:2018
  • Possible consequences with regard to the correct interpretation of mechanical engineering drawings and product liability when applying ISO 2768-1, -2 (withdrawn) and ISO 20457:2018
  • General dimensional and geometric specification (ISO 22081:2021) - rules and limitations

Tolerancing of non-rigid parts (ISO 10579:2013)

  • Difference between rigid and non-rigid parts, specification of clamping conditions, recognising erroneous specifications
  • Drawing indications and free-state modifier

Projected toleranced feature (ISO 1101:2017)

  • Drawing indication for the projected toleranced feature (toleranced feature and datum feature)
  • Typical examples and benefit of using the projected toleranced feature