🌾 Grain Bin Volume Calculator
Calculate partially filled grain bin, silo, or hopper capacity in bushels
Bin Dimensions
Roof Type
Cone Roof
Flat Roof
Bottom Type
Flat Bottom
Hopper Bottom
Fill Level
D=diameter, Hw=wall, Hr=roof,
Hf=fill
📊 Grain Bin Results
Diameter
30 ft
Total Capacity
15,847 bu
Filled Volume
12,723 bu
Fill %
80.3%
Empty Space
3,124 bu
Cubic Feet
15,904 ft³
📝 Step-by-Step Solution
Bin: D = 30 ft, Hw = 20 ft, Hr = 5 ft (cone roof), Flat bottom
Cylinder capacity: V_cyl = π(D/2)²×Hw = π×225×20 = 14,137 ft³
Roof cone capacity: V_roof = (1/3)π(D/2)²×Hr = (1/3)π×225×5 = 1,178
ft³
Total capacity = 15,315 ft³ = 12,252 bushels
Fill level volume = 12,723 bu (grain at Hf=18 ft + peak Hp=3 ft)
📐 Grain Bin Formulas
Cylinder: V = π(D/2)²×H
Cone (roof/peak): V = (1/3)×π(D/2)²×H
Hopper (inverted cone): V = (1/3)×π(D/2)²×Hh
Bushels (US): V_bu = V_ft³ × 0.8 (1 bu = 1.244 ft³)
Bushels: V_bu = V_ft³ / 1.244
Understanding Grain Bins
🌾 Bin Components
Cylinder wall + roof + bottom. Roof can be cone or flat. Bottom can be flat or hopper (inverted cone for gravity unloading).
📏 Bushel Conversion
1 bushel = 1.244 cubic feet. Standard US grain measure. Divide ft³ by 1.244 for bushels.
⛰️ Grain Peak
Grain forms a cone when filled from center. Peak height affects total storage. Angle depends on grain type (~25-30°).
🔻 Hopper Bottoms
Inverted cone at base. Allows gravity unloading. Adds storage below cylinder but reduces walk-on floor.
Frequently Asked Questions
How do I calculate grain bin volume?
Cylinder + roof + hopper. Cylinder: π(D/2)²×H. Cone roof/hopper:
(1/3)π(D/2)²×H. Add components together.
How do I convert cubic feet to bushels?
Divide by 1.244. 1 US bushel = 1.244 cubic feet. Or multiply cubic
feet by 0.8036.
What is eave height vs peak height?
Eave = cylinder wall height. Peak = roof cone height above eave.
Total height = eave + peak.
How does grain peak affect capacity?
Adds volume. Grain cone formula: (1/3)π(D/2)²×Hp. Increases
storage by 10-20% depending on peak height.
What is a hopper bottom bin?
Inverted cone at base. Grain flows out by gravity. Common on farm
bins. Adds capacity below cylinder floor.
How do I measure fill height?
From bin floor to grain surface. For peaked grain, measure to the
edge (lowest point), then add peak separately.
What is the angle of repose?
Natural pile angle. Corn: ~27°, Wheat: ~25°, Soybeans: ~29°.
Determines grain peak height for given diameter.
How accurate is this calculator?
Very accurate for standard bins. Assumes circular cross-section,
cone/flat roof, cone/flat bottom. Real bins may have variations.
What is test weight?
Grain density. Affects weight per bushel. Standard: Corn 56 lb/bu,
Wheat 60 lb/bu, Soybeans 60 lb/bu.
How do I calculate partial fill?
Use fill height Hf. Calculate cylinder volume up to Hf, add hopper
if applicable, add grain peak cone if present.
What about moisture content?
Affects packing. Wet grain packs differently. This calculator
gives volume; actual bushels may vary ±5% with moisture.
Can I use this for silos?
Yes, same geometry. Tall cylindrical silos use same formulas. May
have different roof styles.
How do I find bin diameter?
Measure inside wall to wall. Or check manufacturer specs. Ring
count × ring spacing for bolt-together bins.
What is struck vs heaped capacity?
Struck = level full. Heaped = includes grain cone peak. Our
calculator handles both with peak height input.
How do I calculate weight from bushels?
Bushels × test weight. Example: 10,000 bu corn × 56 lb/bu =
560,000 lbs = 280 tons.
What units does this calculator use?
Feet, meters, or inches. Output in bushels (US) and cubic feet.
All dimensions must use same unit.
How do I measure roof height?
From eave to peak. The cone portion above the cylinder wall.
Typically 15-25% of diameter for standard bins.