Free GD&T Calculator [ + Much More ]
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:
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 | |
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.
GD&T Tutorial Home GD&T Symbols
Recently updated on March 15th, 2024 at 09:13 am