In this article, I will explain two basic methods by which you can change units in AutoCAD drawing. I have also made this video to explain this tip in detail, In case you don’t prefer the video scroll below for the article.
Let’s assume that you have a drawing which is in imperial units (inches) and you want to convert it into metric units (mm), let’s name that drawing Sample.DWG.
Using -DWGUNITS command:
This is an easy method of converting the unit of drawing but it will work only for AutoCAD 2009 and later versions.
Open Sample.DWG drawing (imperial) in AutoCAD and then type -DWGUNITS on the command line (don’t forget to add the dash before command) and press enter. Now, look at the command line prompt which looks like the image shown below.
Here you need to specify unit which you want to use in the current drawing,type the order number of unit and that unit will be applied. In this case, the millimeter option is in third place and hence typing 3 and pressing enter will select millimeter as drawing unit. Similarly, from other prompts use options as shown below.
Linear display format <2>
Linear display precision <4>
Scale objects from other drawings upon insert? <yes>
Match INSUNITS to drawing units? <yes>
Depending on your selection you may or may not see following prompts on the command line. Select yes from both of these prompts.
Scale objects in current drawing to reflect change in units? <yes>
Include objects in Paper Space? <yes>
Your drawing is now converted to metric with millimeter as drawing unit. You can verify the result by measuring the distance between any two points in the drawing, it will now be reported in millimeter instead of inches.
Changing by block import:
This method of converting unit is destructive in nature and you will lose a lot of data from your drawing, mostly named objects like layers, blocks, and linetypes.
Open a new session of AutoCAD and click on New Drawing from the application menu, a template selection window will appear select acadiso.dwt template from this window and click open.
Now type UN on the command line and press enter Units window will appear. Select millimeters from Insertion Scale drop-down menu, you can select any other unit as well as per your own need but for this article, I will stick with millimeters.
Now type I on the command line and press enter, browse your imperial unit drawing Sample.DWG from insert window.
Uncheck Specify On-screen radio button from insertion point, Scale and Rotation panels, also make sure explode radio button is checked in the lower left corner of the Insert window.
If you have followed all these steps correctly then you will see a conversion factor of 25.4 in block unit panel now click OK to close the Insert window.
Your drawing with converted units will be inserted into the new template and now if you check distances in drawing it will be reported in millimeter instead of original inches.
Did you find this tip useful and which method you prefer to convert your drawings from one unit to other? Let me know in comments below.
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I am a mechanical engineer and I have worked with Design, Manufacturing and Training industries but now SourceCAD is my full-time work and I use it to train students all over the world. I also train corporate clients and help them develop the skill set of their workforce.
I am Autodesk AutoCAD Certified Professional and an Autodesk expert elite member. I am a regular contributor of AUGI World magazine and apart from SourceCAD I also develop AutoCAD video courses for Pluralsight and other E-Learning businesses.