GD&T Study Guide 2026
Everything you need to pass the GD&T exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 GD&T Exam Format at a Glance
📚 GD&T Topics to Study (69)
✍️ Sample GD&T Questions & Answers
1. What is the purpose of using multiple datum targets (e.g., A1, A2, A3) to establish a single datum plane?
Multiple datum targets simulate a plane on irregular surfaces (like castings) by defining exact contact points rather than relying on full surface contact.
2. A component drawing requires a surface finish of Ra 0.8 μm on a mating face. The manufacturing engineer proposes lapping instead of grinding. This is acceptable if:
Without a specified process restriction on the surface symbol, any process that achieves the required Ra value is acceptable per drawing intent.
3. What is the role of surface texture in GD&T?
Surface texture, including roughness, waviness, and lay, plays a critical role in GD&T by influencing how mating parts interact. It affects friction, wear, lubrication, sealing, and electrical contact. Specifying appropriate surface texture ensures proper functional contact, prevents premature failure, and achieves desired performance characteristics.
4. A drawing note states 'ALL TOLERANCES ±0.005 UNLESS OTHERWISE SPECIFIED.' A dimension shown as 3.750 +0.010/−0.000 would have which tolerance applied?
A specific tolerance shown on a dimension always overrides the general title block tolerance for that particular feature.
5. Which symbol designates a datum target area in GD&T?
A datum target symbol is a circle divided by a horizontal line; the lower half contains the datum letter and target number (e.g., A1).
6. An MMC modifier is applied to the FRTZF of a composite position callout. What benefit does this provide?
An MMC modifier on the FRTZF allows each feature's tolerance zone to increase (bonus tolerance) as the feature departs from MMC, while still maintaining pattern geometry.