



 
Hi Melissa. If you look at this link you will find that the area of an octagon that measures "w" between the So for 7' 3", that's w = 7.25 feet, and my calculator says: which is reasonable, because the octagon would have less area than a 7.25 x 7.25 foot square, which would be a bit more than 50. The depth you indicated is 5/12 of a foot. So we multiply 43.54 x (5/12) = 18.14 cubic feet. That's how much gravel you'll need. A bit more than 18 cubic feet. Cheers,  


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