Crop farming · Storage
Grain bin bushel calculator.
Bin size and grain depth give cubic feet and bushels, with an optional heaped peak and the weight at a standard bushel weight.
Inputs
Bin capacity
Enter the values.
How many bushels are in a grain bin?
For a bin with level grain: find the area of the floor, multiply by the grain depth to get cubic feet, then multiply by 0.8 to get bushels. Floor area of a round bin is π × radius². University of Nebraska-Lincoln CropWatch gives this method and a shortcut for round bins, Bushels = 0.628 × D² × H, where D is the bin diameter in feet and H is the grain depth in feet.
Worked example. The Nebraska example is a 36-foot diameter bin with 18 feet of grain. Using π = 3.14, CropWatch gets 14,650 bushels. The shortcut gives 0.628 × 36² × 18 = 14,650. This tool uses full-precision π, so the default inputs return 18,322 cubic feet and 14,657 bushels, a difference of 7 bushels. At 56 lb per bushel that much corn weighs about 820,800 lb, or 410 short tons.
Heaped peak. Grain filled through the top forms a cone. The tool adds a cone of one third of the floor area times the peak height, so an 8-foot peak on the 36-foot bin adds 2,714 cubic feet, about 2,171 bushels, for 16,829 bushels. The cone volume is plain geometry, not a CropWatch figure, and real peaks are rarely perfect cones.
Weight. The weight estimate multiplies bushels by the standard bushel weight (56 lb corn, 60 lb soybeans and wheat, 48 lb barley, 32 lb oats, per the University of Georgia planting guide). Actual grain weight depends on test weight and moisture.
Frequently asked questions
How do I calculate bushels in a round bin?
Bushels = 0.628 x diameter squared x grain depth, with both in feet. That is the Nebraska CropWatch shortcut for level grain. It equals the bin floor area x depth x 0.8 bushels per cubic foot.
Why is the answer slightly different from the Nebraska example?
CropWatch rounds pi to 3.14, which gives 14,650 bushels for a 36 ft bin with 18 ft of grain. Using pi at full precision gives 14,657.
Does this include the peak or a hopper bottom?
It counts level grain, plus an optional cone-shaped peak for round bins. A hopper bottom or an unloading cone below the floor level is not included, so add that volume yourself.
How many bushels per cubic foot?
CropWatch uses 0.8 bushels per cubic foot, meaning 1.25 cubic feet per bushel.
Sources
Checked
- University of Nebraska-Lincoln CropWatch: How to Estimate Bushels in a Round Grain Bin
- University of Georgia Extension Circular 813: Planting Guide for Row Crops in Georgia
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Not professional advice
Estimates only. Packing, moisture, grain type and filling method change real capacity. Never enter a grain bin: flowing grain can bury and kill a person in seconds. Follow your local grain safety rules.