Select the Dimension
option 
from the Sketcher
toolbar.
The General Dimensioning Procedure describes how to dimension any type of entity. Since this procedure varies slightly according to the kind of dimension you are dimensioning, specific instructions are provided for dimensioning various entities.
The following procedure describes how to assign dimensions to all entities. The dimensions may be regular units or expressions. Steps 2 and 3 may vary according to the kind of entities you wish to dimension.
To assign a dimension to an entity:
Select the Dimension
option from the Sketcher
toolbar.
Click the entities you want to dimension. For example, to measure the distance between two points, you click two points.
Entities change to bright green as you pass the cursor over them.
Entities change to light green as you select them.
Click the location where you want the dimension to appear. For example, if you are dimensioning a line, click above or below the selected line. A dimension and the Dimension dialog appear.
The dimension appears in blue. By default, the measurement is rounded to 1 decimal place, but you can change that in Preferences.
The Dimension dialog displays the exact value of the dimension.
You can modify the actual dimensions of entities, adjust a displayed dimension's tolerance or precision.
Click anywhere to define the dimension (or click exit or press Enter).
After a dimension is defined, you can delete it, move its location, or modify it, as described in step 3.
See also:
Dimensioning the Sketch for a complete list of the entities you can dimension.