Because so much of what you can do in Illustrator is vector plus effects, a stroke around an object is considered to be just another effect and by default, it’s not accounted for in the measurements of the Control palette. The width and the height are the measurements of the vector itself. Hard to believe? Prove it to yourself. Draw a rectangle with the Rectangle tool (M). Open the Stroke palette if it’s not already open (Window > Stroke). Add a thick stroke in the Stroke palette. Make note of the measurements in the Control palette and change the stroke weight back to zero. No change. Even changing Align Stroke in the Stroke palette from center, to inside, or outside makes no difference.
But what if you need to know the exact measurements of an object including its stroke? You have to change Illustrator’s Default Preferences – Command + K (Control + K on a PC). In the General section, select “Use Preview Bounds.” Now strokes as well as any other effects (like Drop Shadows) will be included in the dimensions.
Tip provided by Jeff Witchel, Certified Adobe® Training Provider.