Jl Audio 15W3-D4 Car Subwoofer "spec 8 inch sub box" Questions

...8 inch subwoofer ranging between 80Hz and 120Hz, the box size required should be around 11 liters, meaning that you will end up with a box of 9 inches high, x 9 inches wide, x 9 inches deep. Or 225mm ...

...spec like 10"deep by 14" squared or 8 deep by 13 squared lamen terms I've Got The Same Subs, I Got A Formula On The Net, Its Dimension Is Aprox 9 D X 24 H x15 W. Although I Have Them In A Home Made ...