When digging, how many inches should I account for my decking?
Typically, you will use the coping height you purchased. If you are using bricks or pavers, etc... Measure the thickness of the stone, and add it to your wall height. If you have bull nose coping, it is normally 2 1/2" but measure to be sure. Cantilever coping is usually 3 1/2".
Auto cover coping varies. Check your coping height, and add it to the wall height.