Building speakers need help

[razakiel666]

Hi as the title I'm gonna build a pair of
Speakers. Using 4 Dayton audio esoteric 7inchers and seas dxt tweeters.
Using the thing in the pictures and mdf for boxes easy to work with they will be sand filled. The problem is i need help with what size to cut the tubes in to get right volume.

 

[razakiel666]

The tubes are 200 in diameter and 800mm in length

 

[PeteMcK]

Volume = π * radius * radius * height