miss (something) by a mile
To fail or fall short (of something) by a very wide margin. I thought she would appreciate such a practical present for her birthday, but it looks like I missed by a mile. He kept boasting about how good he is at horseshoes, but he missed by a mile every time he went up to throw.
miss (something) by a mile
Fig. to fail to hit something by a great distance; to land wide of the mark. Ann shot the arrow and missed the target by a mile. "Good grief, you missed by a mile," shouted Sally.
miss by a mile
Fall short, fail by a considerable amount, as in Your guess as to the winner missed by a mile. This expression employs miss in the sense of "fail to hit something aimed at," a usage dating from the late 1400s, and by a mile for a great distance or interval, so used since Shakespeare's day.