Grain Bin Volume and Capacity Calculator
Calculate the storage capacity of a round grain bin in bushels and tons.
Enter diameter and grain height for accurate volume estimates.
Grain Bin Capacity Grain bins (also called silos or grain tanks) are cylindrical storage structures used to hold harvested grain. Capacity is measured in bushels, the standard unit for grain trading. Knowing exact capacity helps farmers plan storage, manage inventory, and calculate crop value.
The Formula Volume (cubic feet) = pi x (Diameter/2)^2 x Height. Bushels = Volume in cubic feet x 0.8036 (since 1 bushel = 1.2446 cubic feet). For a round bin: Bushels = 0.6283 x Diameter^2 x Height (when diameter and height are in feet).
Cone Top and Peaked Grain When grain is loaded from a center fill, it forms a cone on top. The cone adds storage: Cone bushels = 0.209 x Diameter^2 x Height_of_cone. The angle of repose (how steep the cone is) depends on the grain type. Corn and soybeans: approximately 25-28 degrees. Wheat: approximately 25 degrees. Rice: approximately 36 degrees.
Grain Weights per Bushel Corn (shelled): 56 lbs/bushel. Soybeans: 60 lbs/bushel. Wheat: 60 lbs/bushel. Oats: 32 lbs/bushel. Barley: 48 lbs/bushel. Rice (rough): 45 lbs/bushel. Sunflower seeds: 30 lbs/bushel. These are official “test weights” — actual weight varies with moisture content.
Moisture Content Impact Grain must be dried to a safe moisture level before storage to prevent spoilage. Corn: store at 14% moisture or below. Soybeans: 13%. Wheat: 13.5%. Wet grain takes up more space per bushel of “dry equivalent” — a bin full of 20% moisture corn holds fewer dry-equivalent bushels than the same bin full of 14% corn.
Common Bin Sizes Farm bins range from 18 feet diameter (about 3,000 bushels at 18 ft eave height) to 48 feet diameter (about 30,000 bushels). Commercial elevators use bins up to 105 feet diameter holding 300,000+ bushels. A 1,000-acre corn farm yielding 200 bushels/acre needs 200,000 bushels of storage.