How do u calculate the internal volumne of your sub box???

 

Take all the measurements from the outside of the box (lenght, width, hieght) and subtract the wood thickness from them. Ex.-say your box is 14 inches wide, and you are usuing 3/4 inch wood, you would subtract 1.5 inches, and have 12.5 inches.

Once you have all those measurements, multiply them all, and divide by 1728 (number of cubic inches in a cubic foot). That will give you the volume in cu. ft.