Grain Bin Calculator
Calculate grain bin capacity, bushel volume, and storage costs for round and rectangular bins. This grain bin bushel calculator supports standard bins, peaked roofs, inverted cones, and hopper floors to help you accurately estimate grain storage capacity for corn, soybeans, wheat, and other crops.
Calculate Your Grain Bin Capacity
Bin Configuration
Round Bin Dimensions
Grain Information
Cost Analysis (Optional)
Typical: $3.50-$4.50/bushel
Typical: 2-10¢ per bushel/month
Grain Bin Capacity Formulas
Round Grain Bin Calculations
1. Basic Round Bin Capacity:
\( \text{Bushels} = \pi \times R^2 \times H \times 0.7786 \)
Where: \( R \) = radius (diameter ÷ 2), \( H \) = grain depth, constant 0.7786 = bushels per cubic foot
Alternative quick formula: \( \text{Bushels} = 0.628 \times D^2 \times H \) (where \( D \) = diameter)
2. Peaked Roof Addition:
\( \text{Peak Bushels} = \frac{1}{3} \times \pi \times R^2 \times H_{\text{peak}} \times 0.7786 \)
Cone volume formula: \( V = \frac{1}{3} \times \text{Base Area} \times \text{Height} \)
3. Hopper/Inverted Cone Subtraction:
\( \text{Hopper Loss} = \frac{1}{3} \times \pi \times R^2 \times H_{\text{hopper}} \times 0.7786 \)
4. Complete Round Bin Formula:
\( \text{Total Bushels} = \text{Body} + \text{Peak} - \text{Hopper} \)
Rectangular Bin Calculations
1. Basic Rectangular Bin:
\( \text{Bushels} = L \times W \times H \times 0.7786 \)
Where: \( L \) = length, \( W \) = width, \( H \) = grain depth
2. Conversion Constants:
• 0.7786 bushels per cubic foot (precise)
• 0.8 bushels per cubic foot (simplified)
• 1 bushel = 1.244 cubic feet
• 1 bushel = 2,150.42 cubic inches
How to Use This Grain Bin Calculator
- Select Bin Shape: Choose between round (cylindrical) or rectangular grain bins. Most farm grain storage uses round bins.
- Choose Roof Type: Select flat/level fill for standard storage or peaked if your bin has a conical top that adds storage capacity.
- Select Floor Configuration: Choose flat floor for standard bins or hopper/inverted cone if your bin has a sloped bottom for easier unloading.
- Measure Bin Dimensions: For round bins, measure diameter and grain depth. For rectangular bins, measure length, width, and depth. Use consistent units.
- Enter Peak/Hopper Heights: If applicable, measure the height of the peaked roof or depth of the hopper cone for accurate calculations.
- Select Grain Type: Choose your stored grain to apply correct test weight (lbs per bushel). Common values: corn 56, soybeans/wheat 60.
- Add Cost Information (Optional): Enter construction cost per bushel and storage rates to estimate total investment and ongoing expenses.
How to Measure Your Grain Bin
Measuring Round Bins
- Diameter: Measure straight across the bin at the widest point. Most grain bins have standard diameters (18', 21', 24', 27', 30', 36', 42', 48', 54', 60').
- Grain Depth: Measure from the floor to the surface of the grain. For FSA measurements, take readings at specific locations: center and at 1/6 diameter from the wall.
- Peak Height: Measure from the level grain surface to the highest point of the peaked cone. Use a weighted measuring tape dropped from the top.
- Hopper Depth: Measure from the flat floor level down to the bottom of the inverted cone or hopper.
FSA Grain Bin Measurement Guidelines
USDA Farm Service Agency requires specific measurement procedures for official grain inventory reporting. Measure grain depth at multiple points and calculate equivalent flat level. For partially filled bins, measure at center and eave locations to account for cone formation. Record measurements to the nearest inch for accuracy.
Standard Test Weights for Common Grains
Note: Test weights can vary based on grain moisture content, kernel size, and foreign material. These are USDA official weights for top-grade grains.
Frequently Asked Questions
How do I calculate bushels in a round grain bin?
Use the formula: Bushels = π × radius² × grain depth × 0.7786. For a 36-foot diameter bin (18-foot radius) with 20 feet of grain: 3.14159 × 18² × 20 × 0.7786 = 15,883 bushels. The quick method is: 0.628 × diameter² × depth = 0.628 × 36² × 20 = 16,257 bushels (slightly less precise).
What is the formula for grain bin capacity with a peaked top?
Calculate the cylindrical body first, then add the peak volume using the cone formula: Peak bushels = (1/3) × π × radius² × peak height × 0.7786. For a 36-foot bin with 4-foot peak: (1/3) × 3.14159 × 18² × 4 × 0.7786 = 1,058 additional bushels. Total capacity is body plus peak volume.
How do I figure bushels in a bin with an inverted cone or hopper?
Calculate total cylindrical volume first, then subtract the hopper cone: Hopper loss = (1/3) × π × radius² × hopper depth × 0.7786. For a 30-foot bin with 3-foot hopper: (1/3) × 3.14159 × 15² × 3 × 0.7786 = 551 bushels lost to the cone. Subtract this from the full cylinder calculation.
How much does a grain bin cost per bushel of storage?
New grain bin construction costs range from $3.50 to $4.50 per bushel of capacity as of 2024, including the bin structure and concrete pad. Complete grain center installations with electrical, augers, and accessories cost $7-10 per bushel. Larger bins have lower per-bushel costs due to economies of scale. Used bins offer savings but may lack modern features.
What are typical grain storage costs per bushel per month?
Commercial grain storage rates vary from 2-10 cents per bushel per month depending on location, services, and market conditions. On-farm storage fixed costs (depreciation, insurance, maintenance) average $0.026-0.032 per bushel per month for a 12-month period. Variable costs (electricity, labor) add $0.01-0.02 per bushel.
How accurate is the 0.8 bushels per cubic foot conversion?
The 0.8 conversion is a simplified approximation that overestimates capacity by about 2.7%. The precise conversion is 0.7786 bushels per cubic foot (or 1.244 cubic feet per bushel). For large commercial operations requiring FSA reporting or insurance documentation, use 0.7786. For quick farm estimates, 0.8 provides reasonable accuracy.
Common Grain Bin Sizes and Capacities
Note: Capacities shown are for level-filled bins without peaks. Add 10-15% capacity for peaked roofs.