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Grain Silo & Storage Bin Capacity Calculator Agricultural Operations
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Grain Silo & Storage Bin Capacity Calculator

Determine total grain storage capacity in Winchester bushels, metric tons, and cubic feet, accounting for conical roof peaking and deep-bin pack compaction.

Inside ring diameter
Concrete floor to top eave ring
Total Grain Bin Storage Capacity
58,740 Bushels
1,492 Metric Tons (3,289,440 lbs)
Struck Level Bushels
46,510 Bu
57,906 cu ft cylinder
Deep Pack Factor
1.082 (+8.2%)
+4,460 Bu compaction
Total Usable Volume: 67,557 cu ft (1,913 m³)
Roof Cone Peak Height: 12.8 Feet (Total Peak: 44.8')
Roof Cone Additional Volume: 7,770 Bushels (In Cone)
Grain Total Payload (US Short Tons): 1,645 US Tons
Semi-Truck Loads (1,000 bu/load): ∼59 Semi-Trailer Loads
Evaluated using standard Winchester bushel geometry (1 bu = 1.244456 cu ft) and USDA pack factor curves.

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Grain Silo Volumetrics & Grain Pack Compaction Dynamics

Determining the true storage capacity of corrugated grain bins requires accounting for two non-cylindrical physical factors: the conical peaked grain pile beneath the roof (governed by the crop's natural angle of repose, typically 28°), and the Pack Factor. Because grain is granular and elastic, kernels at the lower levels of tall commercial silos compress and interlock under tremendous overburden weight, packing 5% to 15% more grain mass into the same cubic volume than an uncompressed bushel basket.

Volumetric Governing Equations

  1. Cylinder Volume (V_cyl):
    V_cyl (cu ft) = π × (Diameter / 2)² × Eave_Height
  2. Conical Roof Peak Volume (V_cone):
    For grain peaking at 28° angle of repose:
    Peak Height = (Diameter / 2) × tan(28°) ≈ Diameter × 0.266
    V_cone (cu ft) = (1 / 3) × π × (Diameter / 2)² × Peak Height
  3. Winchester Bushel Conversion:
    Bushels = Volume (cu ft) / 1.244456 = Volume (cu ft) × 0.803564
  4. Deep Bin Pack Factor:
    Per USDA and Iowa State Extension engineering guidelines, pack factor compaction increases with grain column depth:
    Pack Factor ≈ 1.0 + [ Eave_Height (ft) / 400 ] (for grain depths of 20 to 100 ft).
  5. Mass & Tonnage Conversions:
    Total Weight (lbs) = Bushels × Standard Test Weight (lb/bu)
    Metric Tons (MT) = Total Weight (lbs) / 2,204.62

Frequently Asked Questions

What are standard test weights for common grains?

USDA commercial standard test weights per bushel: Shelled Corn: 56 lbs; Soybeans: 60 lbs; Hard Red Winter Wheat: 60 lbs; Barley: 48 lbs; Oats: 32 lbs; Grain Sorghum (Milo): 56 lbs.

Why should grain bins be core-dumped after filling?

When a bin is filled from the top center roof cap, broken kernel fragments, weed seeds, and fine chaff (the "foreign material" or FM core) accumulate directly beneath the fill spout. Core-dumping involves drawing out one or two truckloads from the center bottom sump to invert the peak into a crater, pulling out the trash core and improving aeration airflow.

What is the angle of repose for dry grain?

For clean, dry shelled corn, soybeans, and wheat at 13% to 15% moisture, the natural angle of repose is approximately 28 degrees. Wet grain has a higher angle of repose (32°-35°), while grain with fine powdery chaff may peak steeper.

How many bushels are in a standard grain semi-truck?

A standard tandem-axle hopper bottom grain trailer holds approximately 900 to 1,050 bushels of corn or soybeans, weighing approximately 50,000 to 58,000 lbs of payload under standard 80,000-lb gross highway weight limits.