sub and port displacement

[Lschevy 3]

How do i calculate sub and port displacement? I want to know exactly how much room I have for subs

[Polish 9]

Add it all up and subtract it from the internal volume. So if you have two subs that displace .10 each, that is .20. Then the port displaces .90 which you add to the .20 so the total is 1.10. Then you would subtract 1.10 from the box volume. If it was 6.10, you would be left with 5 cu/ft. Make sure you only calculate the internal port volume, not the entire thing.