Sidewall height is rings times sheet height. Use the height each ring adds to the wall once the sheets overlap. Rings filled can be a part ring, like 6.5, and is counted from the top of the hopper, or from the floor if flat. Leave it blank to fill to the eave. Peak angle is how steep the grain piles. It is about 20 to 30 degrees, depending on the grain and moisture.
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Bushels
Volume is the cylinder plus any hopper cone and grain peak, converted at 1 bushel = 1.2445 cubic feet. Weights are standard bushel weights. Real grain settles and packs, and manufacturers rate bins with their own methods, so the bin maker's rated capacity may differ a little. Use this as an estimate.