Meters to Inches

Inches vs. Meters

It takes 5 vs. 10 characters of careful typing to get the dimensions input correctly.

Combining units in AutoCAD isn’t an automatic task because you can only specify or use one unit type at a time. So what do you do when you’re working on drawing whose units are inches, and you suddenly want to draw something for which you only have metric dimensions? I suggest you go ahead and draw the geometry using meters. However, you will need to scale it accordingly to re-scale the metric entities you created to inches. Originally, they will look too small, about 40 times smaller than reality.

As you might recall, 1 inch = 0.0254 meters. Conversely, 1 meter = 39.3701 inches. You can use those two factors to convert from one unit to the other.

This short LISP routine allows you to select a set of objects and then automatically re-scale them for you accordingly. In the case of converting meters to inches, or Convert to Meters, c2m for short, use the following code:

(defun c2m ()
(setq SS (ssget “\nSelect source objects created using metric units: “)
(setq P1 (getpoint “\Specify base point: “))
(command “_scale” SS “” P1 39.37007874015748)

Notice I used 14 decimal places, instead of the simpler 39.3701 version you will find in most conversion factor tables. This will allow you to make more round trips while minimizing the amount of error you introduce every time you convert from one unit to the other.

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