Add a linear dimension to a drawing to measure between 2 points. 
-  Click Annotate tab
Dimension panel
 (Linear). 
  
 
- Place the cursor at a reference point on an element, such as a wall or a line, or at the intersection of references, such as a join between 2 walls. 
  
The reference point highlights if you can place the dimension there. You can switch through the different reference points of intersections by pressing 
	 Tab. 
  
 
 
- Click to specify the reference. 
 
- Place the cursor on the desired location of the next reference point, and click. 
  
As you move the cursor, a dimension line appears. You can continue to select multiple references, if desired. 
  
 
 
- After selecting a second reference point, press 
  Spacebar to align the dimension to the vertical or horizontal axis. 
 
- When you have reached the last reference point, move the cursor away from the last element, and click. 
  
The dimension displays.