GD&T Symbols Reference Chart

This is your convenient guide for Geometric Dimensioning and Tolerancing (GD&T) symbols.  Click on any link below to lean more about each GD&T symbol or concept. You can also download a PDF version of this information by clicking the button:

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Control Type	Characteristic	GD&T Symbol	Notes
Form	Flatness		Controls form (shape) of size and non-size features. Datum reference is not allowed
	Straightness
	Circularity (Roundness)		Controls form (shape) of size features only. Datum reference is not allowed
	Cylindricity
Orientation No relation between features	Perpendicularity		Controls orientation (tilt) of surfaces, axes, or median planes for size and non-size features. Datum reference required. Optional: Angularity symbol may be used for all orientation controls.
	Parallelism
	Angularity
Location	Position		Locates center points, axes and median planes for size features. Can also control orientation.  See also True Position.
	Profile of a Surface		Locates surfaces by describing a tolerance zone around the surface or line. Can also be used to control size, form, and orientation based on datum reference.
	Profile of a Line
Runout	Total Runout		Controls surface coaxiality Can also control form and orientation of surfaces
	Circular Runout
Location of derived median points.	Concentricity		Locates derived median points of a feature Not common, consider position, runout, or profile instead
	Symmetry

Feature Control Frames: Modifiers

Symbol	Modifier	Notes
	Free State	Only applies if part is otherwise restrained.
	Least Material Condition (LMC)	Useful to maintain minimum wall thickness
	Maximum Material Condition (MMC)	Provides bonus tolerance only for a feature of size
	Projected Tolerance Zone	Useful on threaded holes for long studs
	Regardless of Feature Size (RFS)	Not part of the 1994 standard
	Tangent Plane	Useful for interfaces where form is not required
	Unilateral	Appears in the 2009 version and refers to unequal profile distribution

A Feature Control Frame describes the conditions and tolerances of a geometric control on a part’s feature.

Notes:

“RFS” means regardless of feature size.  It simply means that whatever GD&T callout you make, it is controlled independently of the size dimension of the part.  RFS is the default condition of all geometric tolerances (by rule #2 of GD&T) and requires no callout.

These GD&T symbols are provided as a reference for CNCCookbook’s free GD&T Tutorial. To learn what they mean, clicks the links, read on or check the Table of Contents for more information.

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