Be sure to check out our Free GD&T Wallchart for information on all of the GD&T symbols

Our Comprehensive List of GD&T Symbols.

We conveniently grouped the GD&T Symbols into various categories according to when each is used in. Be sure to click on the links to get more information on each GD&T symbol or concept. We will be adding to this list periodically as we continue to build up our content.

  • All
  • Form
  • Misc Items
  • Orientation
  • Profile

Flatness

GD&T Flatness is a common symbol that references how flat a surface is regardless of any other datum’s or features. It comes in useful if a feature is to be defined on a drawing that needs to be uniformly flat without tightening any other dimensions on the drawing. The flatness tolerance references two parallel planes (parallel to the surface that it is called out on) that define a zone where the entire reference surface must lie.

Least Material Condition (LMC)

Symbol: Category: Feature of Size Definition: Least material condition is a feature of size symbol that describes a dimensional or size condition where the least amount of material (volume/size) exists within its dimensional tolerance. The callout also overrides GD&T Rule#2 or the Regardless of Feature Size rule.  For simplicity: If it is a hole or internal feature: LMC[…]

Straightness

Special Note: Straightness actually has two very different functions in GD&T depending how it is called out. In its normal form or Surface Straightness, is a tolerance that controls the form of a line somewhere on the surface or the feature.  Axis Straightness is a tolerance that controls how much curve is allowed in the[…]

Maximum Material Condition (MMC)

Symbol: Category: Feature of Size Definition: Maximum Material Condition or for short, MMC, is a feature of size symbol that describes the condition of a feature or part where the maximum amount of material (volume/size) exists within its dimensional tolerance. The callout also removes GD&T Rule#2 which states that all geometry tolerances are controlled independently[…]

Cylindricity

GD&T Symbol: Relative to Datum: No MMC or LMC applicable: No Drawing Callout: Description: The Cylindricity symbol is used to describe how close an object conforms to a true cylinder. Cylindricity is a 3-Dimensional tolerance that controls the overall form of a cylindrical feature to ensure that it is round enough and straight enough along[…]

Datums in GD&T

Symbol: Definition: A datum is theoretical exact plane, axis or point location that GD&T or dimensional tolerances are referenced to. You can think of them as an anchor for the entire part; where the other features are referenced from. A datum feature is usually an important functional feature that needs to be controlled during measurement as[…]

Circularity

GD&T Symbol:  Relative to Datum: No MMC or LMC applicable: No Drawing Callout: Description: The circularity symbol is used to describe how close an object should be to a true circle. Sometimes called roundness, circularity is a 2-Dimensional tolerance that controls the overall form of a circle ensuring it is not too oblong, square, or[…]

Profile of a Surface

GD&T Symbol:  Relative to Datum: Optional MMC or LMC applicable: No Drawing Callout: Description: Profile of a surface describes a 3-Dimensional tolerance zone around a surface, usually which is an advanced curve or shape. If it is called out on a curved surface, like a fillet on a welded part, the entire surface where the radius[…]

Profile of a Line

GD&T Symbol:  Relative to Datum: Optional MMC or LMC applicable: No Drawing Callout: Description: Profile of a line describes a tolerance zone around any line in any feature, usually of a curved shape. Profile of a line is a 2-Dimensional tolerance range that can be applied to any linear tolerance. If it is called out[…]

Angularity

GD&T Symbol: Relative to Datum: Yes MMC or LMC applicable: Yes (Uncommon) Drawing Callout: Description: Angularity is the symbol that describes the specific orientation of one feature to another at a referenced angle. It can reference a 2D line referenced to another 2D element, but more commonly it relates the orientation of one surface plane[…]