Geometric Dimensioning and Tolerancing uses 14 symbols across five categories: form, orientation, location, runout, and profile. This page is a quick-reference cheat sheet — what each symbol is called, which category it belongs to, and what it actually controls on a part.

Form

• Straightness — how closely a line element follows a straight line.
• Flatness — how closely a surface follows a flat plane.
• Circularity — how closely a circular cross-section follows a true circle.
• Cylindricity — combined roundness and straightness of a cylindrical feature.

Orientation

• Perpendicularity — a 90° relationship to a datum.
• Parallelism — a parallel relationship to a datum.
• Angularity — a specified angle relative to a datum.

Location

• Position — the location of a feature relative to its true position.
• Concentricity — axis alignment between features.
• Symmetry — even distribution of a feature about a datum plane.

Runout

• Circular Runout — surface variation at a single cross-section during rotation.
• Total Runout — surface variation across the full feature during rotation.

Profile

• Profile of a Line — how well a 2D profile conforms to its true profile.
• Profile of a Surface — how well a 3D surface conforms to its true profile.

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