How to Convert a Drawing from mm to Inches in AutoCAD?

Understanding Units in AutoCAD

AutoCAD supports various unit types, which can be critical when modifying or converting drawings. By default, AutoCAD is set to inches, but many users work with millimeters (mm). This guide will walk you through the steps of converting a drawing from millimeters to inches in AutoCAD 2025.

Step 1: Assess Your Current Drawing Units

Before beginning the conversion process, determine the current unit settings of your drawing. This will help ensure that all elements are correctly recognized and adjusted during the conversion.

1. Open your drawing in AutoCAD.
2. Type UNITS in the command line and press Enter.
3. Note the current unit type displayed in the Units dialog.

Step 2: Prepare for Conversion

To successfully convert the drawing units, it’s essential to prepare the workspace and settings.

1. Save a copy of your original drawing to avoid losing any information.
2. Take note of any dimensions or details that may be affected by the unit change.

Step 3: Change Drawing Units from Millimeters to Inches

Now that you have assessed your current units, it’s time to switch from millimeters to inches.

1. Enter the command -DWGUNITS in the command line and hit Enter.
2. Follow the prompts:
   • Choose the appropriate option for Drawing Units, selecting "Inches."
   • For Drawing Unit Display Formats, you may choose a suitable format (e.g., Architectural).
   • Proceed through the prompts for Linear Display Format and Precision, ensuring they meet your preferences.
3. Confirm selections when prompted. Selecting Yes for scaling should help maintain the relative sizes.

Step 4: Adjust Dimensions and Scale

Once the units are changed, you may need to adjust any dimensions that were originally in millimeters.

1. If any dimensions still display in millimeters, select each and update them manually.
2. You can use a scale factor of 1 inch = 25.4 mm for more precise conversions if necessary.

Step 5: Finalize and Save

After making the unit adjustments and verifying dimensions, finalize your changes.

1. Review your drawing thoroughly to ensure all elements conform to the new unit settings.
2. Save your drawing with a new name or version to distinguish it from the original millimeter version.

Frequently Asked Questions

How can I check if my drawing units are set correctly after conversion?

You can check by typing UNITS in the command line. This will open the Units dialog where you can verify that the unit type displays as inches.

What happens to existing elements in my drawing when I change units?

Existing elements will scale according to the new unit settings. It is advisable to verify their dimensions, as they may not automatically adjust to reflect the change from millimeters to inches.

Can I switch back to millimeters after converting to inches?

Yes, you can revert back by following the same steps using the -DWGUNITS command and selecting millimeters as your new drawing unit. Ensure you check the scaling settings to maintain the drawing’s integrity.