Placement off /cutting off

Hello all. I noticed that my xcarve is off by a tiny bit when attempting to cut something on stock. Example I have a 12” by 12” stock MDF and I want to cut a circle 2 inches from X and 2 inches from Y. When I use the shape tool to place the reference point I use the middle one. Then I put 2 inches Y and 2 inches Y. It seems to be cutting it off by a tad bit. Am I setting the x and y wrong ?

Have you calibrated your X & Y travel?
Say a 10" jog command = 10" actual travel?

No i have not done that!! Thank you very much Ill try it out