and it gave me 5.0781 for box volume

 

I used torres and its accurate

 

hmmm kk back to the drawing board

 

torres don't make sense, unless I am missing something

19.5 x 30 x 15 = 8775 inches cubed
and converting that ft cubed
8775/1728 = 5.07 ft cubed

 

but 19.5 would be my outta, so i'd have to the inner a bit wider and deeper

 

You are not factoring in wood thickness.
Use this calculator: Subwoofer Enclosure Calculators, Parallel, Series, Port Length and Volume

 

oh that looks pretty good, thanks man I appreciate it!

 

Hi, I just wanted to also help. gramser57 is right on the gross vol. My program, at 19"H x 30"W x 15"D is giving me 3.896^3ft gross vol. With the port at 17.5"H x 3"W x 26.25"L @40Hz and all displacement, the net is at 3.028^3ft. I would go with a square type enclosure also, easier to build the port. I hope I have helped and if you have any other questions feel free to contact me.

John