Great posting wish I was as good with figures however;
Something is wrong, these are not the correct measurements for a 5 Gal. bucket,I don't believe.
I use frosting buckets from the donut shop, they measure ;inside, 10 1/4 in. bottom, 11 1/8 in. top, and 12 in. deep to the rim,[ this is actually unusable height as you need room for the lid ], which I believe is close to the measurements you gave.
About 4 + Gal.usable, I believe is all they will hold.
Don't mean to counterdick but just ain't sure about the 5 gal. bucket size you show.