Parametric dimensions resize geometry when you change the dimension value. You can sketch freely without worrying whether or not the geometry is the correct size.
When you edit a sketch dimension, its position adjusts as the sketch geometry updates. When you rotate the view of your sketch, dimensions reorient so you can read them easily.
Parametric dimensions can be set to display parameter values, parameter names, or expressions.
Can dimensions be changed after a feature is created?
As you sketch, the size of the geometry is automatically calculated. If it is acceptable, you can accept its size. Usually, you add dimensions to specify the correct size. You can sketch rough geometry and create a feature from it, then return later to edit the sketch and add dimensions to precisely size the feature.
Units are determined when you choose a template or set one up with custom units.
How can parametric dimensions be specified?
A powerful capability of parametric dimensions is your ability to control them. You can specify dimensions with parameters in a spreadsheet, control dimensions through equations to maintain proportions between geometric elements, or as constant values.
Dimensions constrain sketch size. Consider leaving geometry undimensioned if it changes size or is included in an iFeature that resizes when used in different parts.
If a dimension overconstrains the sketch, you can accept or cancel the dimension. If you accept the dimension, the dimension is saved as a reference parameter. Its value is enclosed in parentheses in the sketch, and updates in response to changes in driving dimensions.
Only normal dimensions can be edited. In an overconstrained sketch, you may have to convert other dimensions to driven (reference) parameters first or remove some dimensions or constraints before you can convert driven dimension to normal dimensions.
How do dimensions work with adaptive features?
To take advantage of adaptive features, you can dimension elements to be a specific size or proportional to other geometry, while leaving other elements undimensioned. If you place a part with adaptive features in an assembly, the undimensioned geometry in the feature can change size and shape when you constrain it to fixed components.
After you place a component in an assembly, you can edit its dimensions or change its parameters. This capability lets you maintain a family of similar parts that must be different sizes in multiple assemblies.
In 2D sketches, diametric dimensions are created by default if a centerline is included in the dimension.
Dimensions control the size of a part. You can express them as numeric constants, variables in an equation, or in parameter files.
You can change the display style of dimensions. When a dimension is not selected, right-click in the graphics window, and select Dimension Display. Choose Value, Name, Expression, Tolerance, or Precise Value.
Dimensions calculated by equations (where, for example, d5=d2) are displayed with a prefix of "fx."

Options to access the Application Options dialog box, and then click the Sketch tab to set preferences for placing overconstrained dimensions and editing a dimension when it is placed.
Show Me how to add and edit dimensions
![]() | You can edit sketch dimensions before or after a sketch becomes part of a feature. If a sketch has not been consumed by a feature, its dimensions are visible and can be edited. After a sketch is consumed by a feature, select the feature in the browser and activate the sketch for editing. To change the dimension display style, right-click in the graphics window and select Dimension Display. Choose Value, Name, Expression, Tolerance, or Precise Value. |
Edit dimensions on unconsumed sketch geometry
To make the current dimension equal to another dimension, enter a dimension number. Dimensions calculated by equations (where, for example, d5=d2) are displayed with a prefix of "fx."
Show Me how to edit a dimension
Edit feature sketch dimensions

to switch off the Driven dimension option. In an overconstrained sketch, you may have to first convert other dimensions to driven (reference) parameters, or remove some dimensions or constraints, before you can convert driven dimension to normal dimensions.You can remove dimensional constraints from a sketch, and allow the sketch to resize as needed. Parts with adaptive features resize in assemblies when they are constrained to fixed geometry.
![]() |
|
Automatically apply sketch dimensions and constraints
Use in addition to the Dimension and constraint commands on the Sketch tab, Constrain panel, to place critical dimensions. You can individually-select, multi-select, and window-select geometry to add or remove dimensions or constraints.

Use the Dimension command to add only the dimensions you need, then use the Automatic Dimensions and Constraints command to calculate all other sketch dimensions and constraints. Autodesk Inventor remembers which dimensions and constraints you added and which are calculated by the system, so that the specific values you need are not replaced.
To begin, use commands on the Sketch tab to create sketch geometry. If desired, use the Dimension command to apply critical dimensions.
Show Me how to use Automatic Dimensions and Constraints
Use Show Dimensions to display feature and sketch dimensions. When dimensions are displayed, you can edit the values.
Change the display style of dimension values
You can show parametric dimensions as nominal values, parameter names, expressions, with tolerances, and precise value. Setting the dimension display style applies to all dimensions in the document.
Value displays the nominal dimension.

Name displays dimension as a parameter name.

Expression displays the dimension as an expression.

Tolerance displays the tolerance for dimensions.

Precise Value displays the dimension value, ignoring any precision setting.

Automatic Dimensions and Constraints
Adds automatic dimensions and constraints to fully constrain a sketch. Use in addition to the Dimension and constraint commands on the Sketch tab, Constrain panel (to place critical dimensions). Autodesk Inventor remembers which dimensions you place with the Dimension and constraint commands and those placed by the Automatic Dimensions and Constraints command so that your added dimensions and constraints are not replaced.

Automatically applies missing dimensions and constraints to selected sketch geometry. | |
Curves | Selects geometry to dimension. |
Dimensions | Default is On. Applies automatic dimensions to selected geometry. Clear check mark to exclude dimensions. |
Constraints | Default is On. Applies automatic constraints to selected geometry. Clear check mark to exclude constraints. |
Dimensions Required | Shows number of constraints and dimensions required to fully constrain the sketch. If either Dimensions or Constraints are excluded from the solution, the number is removed from the total shown. |
Apply | Applies dimensions and constraints to selected geometry. |
Remove | Removes dimensions and constraints, if the associated check box is selected, from the sketch geometry. |
Done | Closes dialog box. |
The Dimension command adds dimensions to a sketch. Dimensions control the size of a part. They can be expressed as numeric constants, as variables in an equation, or in parameter files.
Dimensions calculated by equations (where, for example, d5=d2) are displayed with a prefix of "fx."
Dimensions that overconstrain a sketch (driven) are enclosed in parentheses. They do not resize geometry, but update in response to changes to normal dimensions
Dimension properties - Document settings tab
Changes settings that originate on the Units tab and Default Tolerances tab of the Document Settings dialog box. Settings affect all dimensions in the current document.
| Access: | In the browser, right-click a feature and select Edit Sketch or Show Dimensions. Right-click a dimension, select Dimension Properties, and click the Document Settings tab. Or, right-click in a sketch and select Dimension Display. |
Changes the display type for model dimensions. Click the down arrow to choose an item, then click Apply to see its effect on dimensions.
Value | Shows the nominal dimension. |
Show Name | Shows the dimension as a parameter name. |
Show Expression | Shows the dimension as an expression. |
Show Tolerance | Shows the tolerance for the dimensions. |
Show Precise Value | Shows the dimension value, ignoring any precision setting. |
Linear Dimension Display Precision
Controls the number of decimal places to the right of the decimal in linear dimensions.
Angular Dimension Display Precision
Controls the number of decimal places to the right of the decimal in angular dimensions.
Use Standard Tolerancing Values
Select check box to use the precision and tolerance values set on this tab when creating dimensions.
Linear | Applies a linear tolerance setting to a dimension of a specific precision. |
Angular | Applies an angular tolerance setting to a dimension of a specific precision. |
Export Standard Tolerance Values
Select check box to export dimensions to drawings using the precision and tolerance values set on the Default Tolerance tab.