I know the Worksheet_Change fires for when a user updates a range of
cells and the range of cells is passed to the Worksheet_Change sub.
What about when a cell is changed from a formula? Worksheet_Change
doesn't seem to fire when a cell is changed as a result of a forumula
calucation.

Example:
Cell A2 is calcuated by the value of A1 + 1

If you change A1, A2 now changes as well but the Worksheet_Change is
fired but the Target only includes A1 and Worksheet_Change is not
fired again for A2.

Is there a way to capture the change just on A2?

Obviously on every change i can just check to see if i need to make my
adjustments. But their is a performance reason why i cannot. So i only
want to run if indeed the correct cell has been changed not on every
change.