Introduction to Geometrical Tolerancing

The process of specifying the geometry of parts is known as geometrical tolerancing, and it is often as important as specifying dimensional values. When combined, the use of dimensional and geometrical tolerances is often known as geometrical dimensioning and tolerancing, which is often abbreviated to GD&T.

This course provides the knowledge and skills to enable the fundamental understanding of theory and practice of geometrical dimensioning and tolerancing. For this reason, this course is specially targeted at the design community new to this field. The content is based on selected portions of our ‘Dimensional Measurement User’ course.

This course consists of three modules:

  • Module 1: Fundamentals of dimensional measurement
  • Module 2: Understanding geometrical tolerancing
  • Module 3: Tolerance types


Learners who successfully complete the course and assessments will receive an NPL Certificate of Completion.

Learning Outcomes

  • Understand the relevance of dimensional measurement, including the use of dimensional and geometrical tolerances, to all stages of the engineering process
  • Understand the use of datum systems in dimensional measurement
  • Be able to interpret tolerance frames with and without datum references, and understand the shapes of the associated tolerance zones
  • Be able to interpret tolerance frames for the different geometrical characteristics of form, location, orientation, and run-out