Accurately determining the storage capacity of a grain bin is crucial for farmers and agricultural businesses. It impacts logistics, inventory management, and potential profitability. This calculator helps you estimate the volume of grain a cylindrical bin can hold, expressed in bushels, and the total weight it can store.
How the Calculation Works
The calculation involves a few key steps:
Calculate the Bin's Volume: The volume of a cylinder is calculated using the formula:
Volume = π * (radius²) * height
Where:
π (Pi) is a mathematical constant, approximately 3.14159.
radius is half of the bin's diameter.
height is the height of the grain within the bin (in this case, the bin wall height).
The result of this calculation is typically in cubic feet.
Convert Volume to Bushels: A standard bushel is a unit of volume, but its weight equivalent varies significantly depending on the commodity. The conversion from cubic feet to bushels is an approximation, as the exact conversion can depend on grain density and packing. A common approximation is that 1 cubic foot holds approximately 0.80356 bushels. Therefore:
Capacity (bushels) = Volume (cubic feet) * 0.80356
Calculate Total Weight: Once you have the capacity in bushels, you can calculate the total weight of the grain stored by multiplying the capacity by the grain's bulk density:
Total Weight (lbs) = Capacity (bushels) * Grain Density (lbs/bushel)
Using the Calculator
To use this calculator, simply input the following:
Bin Diameter (feet): The total width of your grain bin.
Bin Wall Height (feet): The vertical height of the bin's cylindrical wall.
Grain Type or Density: Select your grain type from the dropdown. The calculator uses approximate standard bulk densities for common grains. If your grain type or its density differs, select "Custom Density" and enter the specific value in pounds per bushel (lbs/bushel).
Clicking "Calculate Capacity" will provide you with the estimated storage capacity in bushels and the total weight the bin can hold based on the entered dimensions and grain density.
Factors Affecting Capacity
While this calculator provides a reliable estimate, actual grain capacity can be influenced by factors such as:
Grain Condition: Moisture content and grain quality can affect how tightly it packs.
Aeration Systems: Internal structures like aeration tubes can slightly reduce usable volume.
Conical Bottoms/Roofs: This calculator assumes a flat bottom and standard cylindrical shape. Bins with conical bottoms or roofs may have slightly different capacities.
Level of Fill: The calculator assumes the bin is filled to the top of its wall height.
// Conversion factor from cubic feet to bushels
var CUBIC_FEET_TO_BUSHELS = 0.80356;
// Standard densities (lbs/bushel) – for reference
var grainDensities = {
corn: 48,
wheat: 30,
soybeans: 47,
barley: 32,
oats: 26
};
var grainTypeSelect = document.getElementById('grainType');
var customDensityInputDiv = document.getElementById('customDensityInput');
var customDensityValueInput = document.getElementById('customDensityValue');
// Event listener for grain type change
grainTypeSelect.onchange = function() {
if (this.value === 'custom') {
customDensityInputDiv.style.display = 'flex';
// Clear the custom density input if it was previously set and now switching away
customDensityValueInput.value = ";
} else {
customDensityInputDiv.style.display = 'none';
// Set the grainDensity input to the selected standard density if not custom
var densityInput = document.getElementById('grainDensity');
if (densityInput) {
densityInput.value = grainDensities[this.value] || ";
}
}
};
function calculateCapacity() {
var binDiameter = parseFloat(document.getElementById('binDiameter').value);
var binHeight = parseFloat(document.getElementById('binHeight').value);
var grainDensityInput = parseFloat(document.getElementById('grainDensity').value);
var grainType = document.getElementById('grainType').value;
var customDensityValue = parseFloat(document.getElementById('customDensityValue').value);
var resultDiv = document.getElementById('result');
resultDiv.innerHTML = "; // Clear previous results
// Input validation
if (isNaN(binDiameter) || binDiameter <= 0) {
resultDiv.innerHTML = "Please enter a valid bin diameter.";
return;
}
if (isNaN(binHeight) || binHeight <= 0) {
resultDiv.innerHTML = "Please enter a valid bin height.";
return;
}
var effectiveGrainDensity;
if (grainType === 'custom') {
if (isNaN(customDensityValue) || customDensityValue <= 0) {
resultDiv.innerHTML = "Please enter a valid custom grain density.";
return;
}
effectiveGrainDensity = customDensityValue;
} else {
effectiveGrainDensity = grainDensityInput;
if (isNaN(effectiveGrainDensity) || effectiveGrainDensity <= 0) {
// If user selected a type but didn't enter a specific density, try to use the default for that type
if (grainDensities[grainType]) {
effectiveGrainDensity = grainDensities[grainType];
document.getElementById('grainDensity').value = effectiveGrainDensity; // Update input field for clarity
} else {
resultDiv.innerHTML = "Please select a grain type or enter a custom density.";
return;
}
}
}
// Calculate radius
var radius = binDiameter / 2;
// Calculate volume in cubic feet
// Volume = π * r² * h
var volumeCubicFeet = Math.PI * Math.pow(radius, 2) * binHeight;
// Convert volume to bushels
var capacityBushels = volumeCubicFeet * CUBIC_FEET_TO_BUSHELS;
// Calculate total weight in pounds
var totalWeightLbs = capacityBushels * effectiveGrainDensity;
// Format the results
var formattedCapacity = capacityBushels.toFixed(2);
var formattedWeight = totalWeightLbs.toFixed(0); // Whole numbers for weight
// Display the results
resultDiv.innerHTML = "Capacity: " + formattedCapacity + " bushelsEstimated Weight: " + formattedWeight + " lbs";
}