This issue occurs because the shapes in a stencil are measured in the default measurement units for that stencil. Shapes from a stencil that uses US units are measured in feet and inches. Shapes from a stencil that uses metric units are measured in millimeters.
Therefore, when you add a shape to a drawing, the Width and Height boxes in the Size & Position window display the values for that shape in the shape's default measurement units.
Note If you resize the shape, the width and height values in the Size & Position window change to match the new measurement settings for the drawing.