Which of the following is not a form tolerance?

• A. Position
• B. Flatness
• C. Straightness
• D. Circularity

Answer: (D)

In GD&T, form tolerances specify the actual shape of a feature. They control how much a surface or element can deviate from an ideal geometric form. The common form tolerances are straightness, flatness, circularity (roundness), and cylindricity. Circularity, in particular, limits how far a cross-sectional contour can deviate from a perfect circle within a plane, and that is a classic form tolerance.

Location or position tolerances, on the other hand, govern where a feature is located relative to datum references or other features, not its shape. So the tolerance that is not a form tolerance is the one that controls location—the position tolerance. The other options listed—flatness, straightness, and circularity—are all form tolerances.