Sure, sounds easy enough, but check out the thread I have in this section about cu. ft.
There are actually two lengths of vent internal to the box.
My T1 12" woofer displacement is 0.08.
H-14" -1.5"
W-36" -1.5" - another 1.5 due to the two thicknesses of the vent
D-13.5" -1.5" -another...