GD&T Cheat Sheet 2026

The 30 highest-yield GD&T facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. In a worst-case tolerance stack-up, how are individual tolerances combined? → They are arithmetically added, assuming all tolerances at their maximum
2. Which of the following is the primary reason for applying a positional tolerance at Maximum Material Condition (MMC)? → To allow for the use of functional gages and provide bonus tolerance for manufacturing.
3. When interpreting a composite feature control frame, what is the term for the tolerance zone defined by the upper segment? → Pattern-Locating Tolerance Zone Framework (PLTZF)
4. In a standard Datum Reference Frame (DRF), what is the minimum number of points of contact required for the primary datum feature to constrain the part? → Three points
5. Under ASME Y14.5, what is the default geometric tolerance condition when no modifier is shown? → Regardless of Feature Size (RFS)
6. What does Rule #1 (the Envelope Principle) state in ASME Y14.5? → A feature of size's surface must not violate a perfect-form envelope at MMC
7. What does the term 'clearance fit' refer to in GD&T? → A fit that allows for movement between parts.
8. What is the primary purpose of tolerance stack-up analysis in GD&T? → To determine the worst-case variation in an assembly due to accumulated tolerances
9. What is the purpose of the perpendicularity symbol in GD&T? → Ensures a feature is square to a reference surface.
10. For an internal feature (hole) at MMC with a position tolerance, virtual condition equals: → MMC minus the geometric tolerance
11. What is a 'loop diagram' used for in tolerance stack-up analysis? → To identify which dimensions contribute to a critical assembly gap or interference
12. What does the surface finish symbol '⧫' represent in GD&T? → The surface roughness of a feature.
13. A material condition modifier (MMC or LMC) can be applied in the feature control frame for which of the following geometric tolerances? → Perpendicularity
14. What does the symbol x signify in GD&T? → Multiplication factor for tolerances.
15. What does the datum feature symbol ⊖ in GD&T signify? → The location of the datum feature.
16. What is the purpose of a profile of a surface in GD&T? → To control the outline of a feature.
17. How does a clearance fit impact the functionality of mechanical components? → It allows movement between components.
18. Which symbol is used to define the origin of a datum in GD&T? → A rectangle symbol.
19. When a feature control frame is attached to an extension line or dimension line (not a leader to the surface), what does this indicate? → The tolerance applies to the derived axis or center plane of the feature
20. Which symbol in GD&T represents the concept of 'true position'? → ⟘.
21. What does a 'sensitivity factor' (influence coefficient) represent in an advanced tolerance stack-up analysis? → A multiplier indicating how a dimension's variation influences the assembly gap output
22. How are datum features typically indicated in GD&T? → By a rectangle symbol.
23. A functional (go) gauge designed to check a pin is sized to which boundary? → Virtual condition
24. When does a title-block general tolerance apply to a dimension on an engineering drawing? → When the dimension has no explicit tolerance callout and is not a basic dimension
25. What does the 'perpendicularity' symbol define in GD&T? → Defines a 90-degree angle between features.
26. A three-part assembly has dimension tolerances of ±0.2 mm, ±0.3 mm, and ±0.1 mm. What is the RSS total tolerance? → ±0.374 mm
27. Virtual condition applies specifically when which modifier is called out in the feature control frame? → MMC (Maximum Material Condition)
28. What does a reference dimension (shown in parentheses) mean on a drawing? → It is provided for information only and is not used for inspection or part acceptance
29. Which of the following best describes 'allocating tolerances' in a tolerance stack-up study? → Distributing the total assembly tolerance budget among individual component dimensions
30. When multiple geometric controls are applied to the same feature (e.g., both flatness and profile), how must the part conform? → It must satisfy all controls simultaneously — none overrides another