Grain Bin Capacity Calculator

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Bikash Sah is the founder of SuperEasyCalc and a Full Stack Developer focused on building practical web applications and online calculators. He creates tools that make everyday calculations easier to perform and understand.

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ESTIMATED CAPACITY
Grain Capacity 0 bu US Bushels (Level Full)
Total Volume 0.0 ft³ Cubic Space

How Bin Capacity is Calculated (Example):

  • Step 1: Identify dimensions: Bin Diameter = 30.00 ft, Eave Height = 20.00 ft, Roof Height = 8.00 ft.
  • Step 2: Find the Radius (r) = Diameter ÷ 2 = 15 ft.
  • Step 3: Calculate Cylinder Volume = π × r² × Eave Height = 3.14159 × 15² × 20 = 14,137 ft³.
  • Step 4: Calculate Roof Cone Volume = (1/3) × π × r² × Roof Height = (1/3) × 3.14159 × 15² × 8 = 1,885 ft³.
  • Step 5: Total Volume = 14,137 + 1,885 = 16,022 ft³.
  • Step 6: Convert to US Bushels (1 ft³ = 0.80356 bu) = 16,022 × 0.80356 = 12,875 Bushels.

Note: This provides the level-full volume; actual capacity may vary by 3-5%.

What Is a Grain Bin Capacity Calculator?

A grain bin capacity calculator is a tool that converts your bin’s dimensions into how many bushels of grain it can hold. You enter the shape, diameter or length/width, eave height, and roof height, and it returns your storage capacity in US bushels.

It works for the two most common bin shapes: round bins with a cone-shaped roof, and square or rectangular bins with a pyramid roof. Enter your numbers once, and you’ll see both the cubic footage and the bushel total, no formulas or manual math required.

If you manage grain storage, plan harvest logistics, or just need a quick number before buying or building a bin, this tool gets you there without pulling out a calculator app and a formula sheet.

How to Use this Calculator tool

Getting your result only takes a few steps:

Pick your bin shape

Choose round or square/rectangular.

Enter your dimensions

Diameter for round bins, or length and width for square bins.

Add your heights

Enter eave height and roof height.

Get your result

Your capacity appears right away, shown in both cubic feet and US bushels.

Working & Formula Behind this Calculator

The math behind a grain bin capacity calculator comes down to volume. Once you know the volume in cubic feet, converting to bushels is simple: one cubic foot equals about 0.8036 US bushels. This figure is based on the Winchester bushel, the standard used across US grain storage and handling.

For round bins: The bin is treated as a cylinder topped with a cone.

  • Cylinder volume = pi × radius² × eave height
  • Cone volume (roof) = one-third × pi × radius² × roof height

Add the two together, then multiply by 0.8036 to get your bushel count.

For square or rectangular bins: The bin is treated as a box topped with a pyramid.

  • Box volume = length × width × eave height
  • Pyramid volume (roof) = one-third × (length × width) × roof height

Add those together and apply the same bushel conversion.

This is why the calculator asks for eave height and roof height separately. The straight walls and the roof are two different shapes, and skipping the roof volume will always give you a low estimate.

Example: Estimating Storage for a Farm Project

Say you’re an agriculture student building a farm management case study, and your assignment asks you to estimate how much corn a bin can realistically store. You’re given a round bin: 30 ft diameter, 20 ft eave height, and an 8 ft roof. Here’s how it plays out:

  • Radius = 30 ÷ 2 = 15 ft
  • Cylinder volume = pi × 15² × 20 = 14,137 ft³
  • Cone volume = one-third × pi × 15² × 8 = 1,885 ft³
  • Total volume = 14,137 + 1,885 = 16,022 ft³
  • Bushels = 16,022 × 0.8036 = about 12,875 bushels

Instead of running that math by hand, you’d plug the same three numbers into the calculator above and get the same answer in a couple of seconds, plus the cubic footage for your report.

Frequently Asked Questions

How many bushels does a 30-foot grain bin hold?

It depends on the eave height and roof height, not just the diameter. A 30 ft diameter bin with a 20 ft eave and an 8 ft roof holds around 12,875 bushels. Change the eave height and the number moves quite a bit, so always measure the actual wall height before you rely on a figure.

What is the formula for grain bin capacity in bushels?

Find the volume in cubic feet first (cylinder plus cone for round bins, or box plus pyramid for square bins), then multiply by 0.8036 to convert to US bushels.

Does grain bin capacity include the roof space?

Yes, and it should. The cone or pyramid at the top adds meaningful volume, especially on taller bins. Leaving it out will underestimate your true capacity.

How accurate is a grain bin capacity calculator?

It gives you the level-full volume based on the dimensions you enter. Actual capacity can vary by around 3 to 5% depending on settling, fill method, and bin construction, so treat the result as a strong planning estimate rather than an exact fill number.

Can I use this calculator for bins measured in meters?

This version is built for feet and US bushels, which matches how most US grain bins are measured and sold. If your dimensions are in meters, convert to feet before entering them.