How tall is ceiling?\n\nIs the room closed or open to other rooms? If open to other rooms\/hallways you need to add that in also. \n\nBasically you calculate cubic feet of volume the sub must pressurize.\n\nOh man then add quite a bit more. Open to foyer, hallway and kitchen doorway. Dude. I cant even calculate 8ft ceilings. The angles are not even. I will try to walk you through. You walk into foyer about 8 ft long wall on left. In that walk on the right is a dining room. You walk into the living room from there, the doorway to dr is open. You are in the bottom left of the rectangle. Immediately to the right is sitting area, left is a long hallway to br's. On the far right is the doorway to the kitchen. So 26 feet long and 15 deep with foyer, kitchen doorway and dining room open to the box.