GD&T Symbols Reference Chart

Controls how straight a surface line element or axis must be. A pure form control — no datum reference required.

All points on a planar surface must lie between two parallel planes separated by the tolerance value. Self-referencing — no datum.

Also called roundness. Each circular cross-section of a cylinder, cone, or sphere must lie between two concentric circles in the same plane.

All surface points of a cylinder must lie between two coaxial cylinders. Combines straightness, circularity, and taper — the most comprehensive form control.

Controls a surface or axis at a specified angle (other than 0° or 90°) relative to a datum plane or axis.

Controls a surface or axis at exactly 90° relative to a datum plane or axis. Commonly applied to holes, pins, and mating faces.

Controls a surface or axis equidistant from and parallel to a datum plane or axis within a specified tolerance zone.

The most widely used GD&T control. Defines the maximum permissible deviation of a feature's center from its theoretically exact (true) position.

All median points of a cylindrical feature must lie within a cylindrical tolerance zone coaxial with a datum axis. Difficult to verify; often replaced by runout or position.

Median points of a non-cylindrical feature must be symmetric about a datum plane. Removed from ASME Y14.5-2018 but still widely referenced in legacy drawings.

Controls the shape of individual 2D cross-sections (line elements) of a surface relative to a true profile. Datum reference is optional.

Controls the full 3D form, and when combined with a datum, the location and orientation of a complete surface. The most comprehensive profile control.

Controls wobble of each individual circular cross-section as a part rotates 360° about a datum axis. Combines circularity and coaxiality per circular slice.

Controls wobble of the entire cylindrical or planar surface simultaneously during a full 360° rotation about a datum axis. Encompasses all surface elements.

Feature has the maximum amount of material: smallest hole, largest shaft. Allows bonus tolerance as the feature departs from MMC.

Feature has the least amount of material: largest hole, smallest shaft. Allows bonus tolerance as the feature departs from LMC.

Tolerance applies regardless of actual feature size. The default in ASME Y14.5-2009 and later; the S modifier is rarely shown explicitly.

Projects the tolerance zone above or below the feature — typically used with threaded holes and press-fit pins to control the engagement zone.

Indicates the tolerance zone is cylindrical rather than a planar band. Placed before the numeric tolerance value in the feature control frame.

Measurement taken with the part unconstrained (no fixtures). Used for non-rigid or flexible parts per ASME Y14.5.