how do i found the cubic feet of my box?

[kyleg94cavy]

i am going to build a big ported box for my 15" l7 and i'm not sure how to find the cubic feet. i want it to be the size that kicker says. i listen toa lot of rap, i want it to be very loud..and tuned to a low frequency so it is really loud..

[Gauntlet]

Dont' tune it that low....mid-30's or so.

As far as finding volume....L x W x H / 1728. Be sure to factor in wood thickness, port displacement, sub displacement, and any bracing displacement (if applicable)