GD&T Reference

Controls how far a feature of size may drift from its theoretically exact location, usually from a datum reference frame.

Controls surface waviness or bow by requiring all points of a surface to fit between two parallel planes.

Controls the median points of opposed surfaces so they remain centered about a datum center plane.

Establishes the theoretically exact point, axis, line, or plane used as the anchor for measuring related GD&T controls.

Controls how much a surface line or derived median line may bend away from perfect straight form.

Controls a surface, line, or axis at a specified basic angle relative to a datum.

Controls a surface or axis so it remains square to a datum plane, line, or axis.

Controls every point on a 3D surface within a boundary that follows the true surface profile.

Describes the size condition where a feature contains the most material: smallest hole or largest pin.

Controls derived median points of a cylindrical feature relative to a datum axis.

Controls how much a surface varies as the part rotates through 360 degrees around a datum axis.

Controls a surface or axis so it remains parallel to a datum while staying inside a tolerance envelope.

Controls how close each circular cross-section of a round feature is to a true circle.

Controls variation of an entire surface as the part rotates 360 degrees about a datum axis.

Controls how closely the full length of a cylindrical feature conforms to a perfect cylinder.

The boxed GD&T sentence that names the control, tolerance, modifiers, and datum references for a feature.

Controls a 2D cross-section of a line or curve within a tolerance band following the true profile.

The size condition where a feature contains the least material: largest hole or smallest pin.

The default condition where geometric tolerance is independent of the actual feature size.

The default ASME rule that limits feature form by the perfect-form envelope at maximum material condition.

A profile modifier that shifts the profile tolerance zone unequally inside and outside the true profile.

An ASME modifier that separates size control from form control for the associated feature.

An ISO symbol that makes size control form through the perfect-form envelope at MMC.

Identifies a specific point, line, or area used to establish a datum from controlled contact locations.

Indicates separated surfaces or feature segments are to be treated as one continuous feature.

Extends a tolerance zone beyond the feature surface to protect fastener clearance in assembly.

Marks a dimension or tolerance that must be evaluated while a non-rigid part is unrestrained.

A drawing note that requires inspection while the part is fixtured, fastened, or otherwise restrained.

Applies a surface control to a simulated tangent plane made from the high points of a surface.

Defines a flat-bottomed cylindrical recess coaxial with a smaller hole.

Defines a shallow flat-bottomed cylindrical cleanup area around a hole.

Defines a conical recess used so a flathead fastener can sit flush or below the surface.

Indicates a circular feature is dimensioned by its full diameter.

Indicates a square feature so one size dimension controls both equal sides.

Indicates a circular feature is dimensioned by radius, or half of its diameter.

Defines a radius that must also be a smooth, fair curve without reversals.

Indicates the radius value applies to a spherical feature.

Indicates the diameter value applies to a spherical feature.

Indicates the depth of a hole, slot, counterbore, or similar feature.

Identifies the required origin surface or location from which a dimension must be measured.

Marks where mold or die segments meet on a cast, molded, or forged part.

Indicates a dimension value is measured along a curved outline rather than as a chord.

Defines a taper as the ratio of diameter change to length change.

Defines a flat taper as the ratio of height change to length change.

Uses a count plus X to apply one dimension or requirement to repeated identical features.