This line is 36 inches, for scaling other items
 

I was thinking of putting OG to work helping lay out a new office space. I have a scan of the layout of the space but I have no dimensions. I can assume the front door is 36 inches wide, so I've drawn a line in OG over the doorway and this line is 17/32 inches long.

Is there a way I can tell OG that 17/32 = 36 and then it can help me draw rectangles to scale that match the size of desks I need to fit?

Thanks.

I believe this is a PRO feature only (not sure though).... You can use the Canvas Size Inspector to set a "Custom" scale. That should do what you are looking for.