How to Add Diameter Dimension in AutoCAD Quickly and Easily

To add a diameter dimension in AutoCAD, use the DIMDIAMETER command or select the Diameter option in the Dimension tool. Click on the circle or arc you want to measure, and AutoCAD will display the diameter dimension with the diameter symbol (Ø).

Syntax

The basic syntax to add a diameter dimension in AutoCAD is:

• DIMDIAMETER - Command to start diameter dimensioning.
• Select the circle or arc to dimension.
• Place the dimension line where you want it to appear.

You can also access this by typing DIM and then choosing the Diameter option from the dimension toolbar.

autocad command

Command: DIMDIAMETER
Select circle, arc, or circle edge: <select the object>
Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: <click to place dimension>

Output

Diameter dimension with Ø symbol displayed on the selected circle or arc

Example

This example shows how to add a diameter dimension to a circle in AutoCAD:

1. Type DIMDIAMETER and press Enter.
2. Click on the circle you want to dimension.
3. Move your cursor to position the dimension line and click to place it.

The diameter dimension with the Ø symbol will appear, showing the circle's diameter.

autocad command

Command: DIMDIAMETER
Select circle, arc, or circle edge: (click on circle)
Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: (click to place dimension)

Output

Diameter dimension line with Ø symbol and numeric diameter value displayed on the drawing

Common Pitfalls

Common mistakes when adding diameter dimensions include:

• Trying to dimension a non-circular object with the diameter tool, which will not work.
• Not selecting the circle or arc correctly, causing no dimension to appear.
• Placing the dimension line too close or overlapping other objects, making it hard to read.
• Confusing radius and diameter dimensions; use DIMRADIUS for radius.

Always ensure you select a circle or arc and place the dimension clearly.

autocad command

Wrong:
Command: DIMDIAMETER
Select circle, arc, or circle edge: (click on a line, not a circle)
Result: No dimension created or error message

Right:
Command: DIMDIAMETER
Select circle, arc, or circle edge: (click on circle)
Result: Diameter dimension created with Ø symbol

Output

Error or no dimension when selecting non-circular object; correct diameter dimension when selecting circle

Quick Reference

Command/Option	Description
DIMDIAMETER	Starts diameter dimension command
Select circle or arc	Choose the object to dimension
Place dimension line	Click where dimension text and line appear
DIMRADIUS	Use for radius dimension instead of diameter
Dimension toolbar	Access diameter option from dimension dropdown

Key Takeaways

Use the DIMDIAMETER command to add diameter dimensions to circles or arcs.

Always select a circular object to avoid errors or no output.

Place the dimension line clearly to keep your drawing readable.

Use DIMRADIUS if you need radius dimensions instead of diameter.

Diameter dimensions include the Ø symbol automatically.