Calculate the storage capacity of your grain bin in bushels and the corresponding grain weight. This calculator accounts for both the cylindrical wall section and the conical peak (or hopper cone) on top, using standard test weights for different grains.
Enter your bin diameter, cylinder wall height, cone/peak height, and select the grain type. The calculator computes the total volume in cubic feet, converts to bushels, and estimates the total grain weight in tons.
Cylinder Volume (cu ft) = ฯ ร rยฒ ร H_cylinder
Cone Volume (cu ft) = (1/3) ร ฯ ร rยฒ ร H_cone
The cone formula accounts for the peaked grain surface at the top of the bin (or the hopper cone at the bottom). The angle of repose for most grains is about 20-25 degrees, giving a cone height roughly 0.18-0.23 ร diameter.
Total Volume = Cylinder Volume + Cone Volume
Bushels = Total Volume (cu ft) รท 1.244
The constant 1.244 cu ft/bu is the standard volume of one Winchester bushel (1.2445 cu ft).
Grain Weight = Bushels ร Test Weight (lb/bu)
A bin 30 ft in diameter, 20 ft cylinder height, 5 ft cone peak: Radius = 15 ft. Cylinder volume = ฯ ร 15ยฒ ร 20 = ฯ ร 225 ร 20 = 14,137 cu ft. Cone volume = (1/3) ร ฯ ร 15ยฒ ร 5 = 1,178 cu ft. Total = 15,315 cu ft.
Bushels = 15,315 รท 1.244 = 12,311 bu. For corn at 56 lb/bu: Weight = 12,311 ร 56 = 689,416 lb = 344.7 tons.
1. Measure the bin diameter (inside wall to inside wall). 2. Enter the cylinder wall height (from floor to the top of the vertical wall, not including the roof). 3. Enter the cone height โ the height of the peaked grain above the wall (or the hopper cone depth). 4. Select the grain type for the correct test weight. 5. Note grain moisture โ higher moisture increases weight per bushel slightly. Click Calculate.
Grain bin capacity planning is essential for harvest logistics, storage management, and marketing decisions. Knowing your bin capacity helps you plan harvest flow, determine how many bins you need, and calculate the value of stored grain. The 1.244 cu ft/bushel conversion is standard, but actual bushels can vary by 2-5% depending on grain packing, moisture, and foreign material. For hopper-bottom bins, subtract the hopper cone volume from the cylinder if the cone is below the floor, or add it if grain fills the hopper.
Common mistakes: Forgetting the cone peak โ a fully filled bin with a peaked surface holds 5-15% more than the cylinder alone. Measuring outside diameter instead of inside โ wall thickness can reduce capacity by 1-3%. Using the wrong test weight โ always use the actual test weight from your grain, not the standard, especially for stressed or drought-affected grain. Ignoring aeration ducts and support beams that displace grain volume.
โ Expert Reviewed: This calculator and its content have been reviewed by agricultural experts. Formulas are based on standard extension service recommendations.