Here is the shortcut math I do in my head in the field when I need a quick answer and don’t have a calculator.
If your concrete wall is 12 inches thick, it’s easy. So just assume it is for now. Take the length of the wall in feet, multiply it by the height of the wall in feet, then multiply that times 1 foot (12 inches).
Length=10 - - Height=8 - - Thickness=1 — – 10×8x1 = 80
Now you have the answer in cubic feet. There are 27 cubic feet in a yard. Divide your sum by 27. Now you cubic yards of concrete.
If the wall is only 8 inches thick, remember that 8 is two thirds of 12, so just multiply your sum times .666…(2/3rds) to subtract the difference. If you have a 10 inch wall, 10 is about .833 percent of 12, so just multiply your sum by .833.
If you want to include the footing in the calculation, you could add 2 feet to the height of the wall, because a footing runs the whole length, and it’s like a 2 foot wall laid on it’s side under the vertical wall.