How to Change Units from Meters to Millimeters in AutoCAD

Changing units from meters to millimeters in AutoCAD involves modifying the drawing settings to ensure your drawings reflect the desired measurement system. This guide will walk you through the steps needed to complete this task effectively.

Accessing the Drawing Setup

1. Open AutoCAD: Launch your AutoCAD 2025 application.
2. Navigate to Drawing Setup: Click on the ‘Utilities’ menu located at the top of the screen. Choose ‘Drawing Setup’ from the dropdown options. This will open the Drawing Setup dialog box.

Modifying Drawing Units

1. Select the Units Tab: Once the Drawing Setup dialog is open, click on the ‘Units’ tab. This section allows you to adjust the units used in your drawing.
2. Change Unit Type: From the ‘Drawing Units’ dropdown menu, select ‘Millimeters’. It’s crucial to select this option to convert your unit setting correctly.
3. Confirm Changes: After making your selection, click ‘OK’ to apply the changes. The drawing will now utilize millimeters as the primary measurement.

Scaling Existing Drawings (if necessary)

1. Scaling Objects: If you have objects that were drawn in meters and now need to be converted to millimeters, you might want to scale them correctly. To scale these objects:
   • Select the objects you wish to scale.
   • Type the SCALE command in the command line and hit Enter.
   • Specify a base point and then enter ‘1000’ (since 1 meter equals 1000 millimeters) to adjust their size accordingly.

Verifying Unit Changes

1. Check Current Units: To ensure the changes have taken effect, open the Drawing Setup dialog again and navigate to the Units tab. Verify that ‘Millimeters’ is displayed in the Drawing Units section.

Default Units for New Drawings

1. Setting Default Units: To ensure that every new drawing defaults to millimeters, go to the ‘Tools’ tab on the toolbar.
   • Click on ‘Options’ and navigate to ‘Document Settings’.
   • Access the ‘Units’ tab and confirm that ‘Millimeters’ is selected to ensure this setting is applied to all new drawings moving forward.

Changing Units in Existing Drawings

1. Open Existing Files: If you are working with an existing file and want to change its units:
   • Enter the UNITS command in the command line.
   • Change the unit type to ‘Millimeters’ as described previously, then confirm with ‘OK’ to apply.
   • Note that changing units will convert the display of existing values according to the new measurement system.

FAQ

1. What happens to dimensions when I change from meters to millimeters?
When you change the units, all dimensions will automatically update to reflect the new unit system; however, scaling may be required for objects that were drawn with specific measurements in mind.

2. Can I switch back to meters after changing to millimeters?
Yes, you can revert your settings to meters by following the same steps outlined above and selecting ‘Meters’ from the Drawing Units dropdown.

3. Do I need to adjust my drawings if I change the unit settings?
Yes, depending on how your drawings were created prior to the unit change, you may need to resize or rescale existing objects to maintain the intended design measurements accurately.