box building formula

What is the formula again for figuring out the square feet of a box that has a angle in it like 19"h X 52"w X top 4"d X bottom 8"d

what is the formula that you times then divide for the top being 4" and the bottom being 8" i hope this makes sense

A couple of different ways.  Look at the Volume Calculators.  Go to wedge 2, and turn your box on its side so that it looks like the diagram:  height 1 is 8", height 2 is 4".  This calculator figures interior space when you measure outside dimensions and input the wall thickness.

Wedge 1 and Rectangular calculations can be combined, because if you draw a straight line down from the top you'll have a simple wedge and a rectangle.

If you measure interior dimensions, you can use the equation:  1/2 base X length X height for the wedge, and the regular W X L X H for the rectangle.  For either of these, you get cubic inches, which when divided by 1728 gives you cubic feet.

i guess i am lost here i found a site that had some other way to do it that added the top dimension and the bottom dimension and divided it by 5 or something and that have gave that number to be added into the equation

Leaving the calculators out of the picture, if you gave interior dimensions of your box in your first post, then divide the box into a wedge and a rectangle as I showed above.  The wedge would be 1/2 base X length X height:  2 X 52 X 19 = 1976 cu. inches.  The rectangle would be 4 X 52 X 19 = 3952.  Add the totals = 5928.  5928 divided by 1728 = 3.43 cu. ft.