Grain Bin Capacity Calculator

Frequently Asked Questions

How many bushels are in a cubic foot?

One cubic foot holds about 0.8036 bushels, since a struck bushel occupies 1.2445 cubic feet. This factor is built into every grain capacity chart.

Should I use bin height or grain depth?

Use the actual grain depth to estimate what is currently stored; use the full bin height only when the bin is completely full to the eave.

Does the peak of grain count?

A full bin usually carries a cone of grain above the eave that adds extra bushels. Add it separately with a cone volume for a precise full-bin figure.

Does grain type change capacity?

The volume-to-bushel factor is constant, but test weight and moisture affect how many marketable bushels and how much actual weight that volume holds.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

A round grain bin is just a cylinder, and its capacity is pure geometry once you know the diameter and how deep the grain sits inside it. This calculator computes the cylinder's volume in cubic feet from the bin's inside diameter and the depth of grain, then converts that volume to bushels using the standard factor of 0.8036 bushels per cubic foot - the dry, struck (heaped-level) bushel that every elevator and grain table is built around. Enter the full bin height for total capacity, or the current grain depth to see how much is in storage right now. It is the same calculation grain tables in your bin manufacturer's manual use; the only inputs that matter are diameter and depth, because the round shape and the bushel constant do the rest.

Formula / Method

Volume (cubic ft) = π × (diameter ÷ 2)² × grain depth, the standard cylinder formula with radius equal to half the diameter. Bushels = volume (cubic ft) × 0.8036, where 1.2445 cubic feet equals one struck bushel, so its reciprocal 0.8036 converts the other way. Use the bin's inside diameter and the actual grain depth, not the bin's overall height, unless the bin is full. The tool rejects zero or negative dimensions. Note this gives the cylindrical (sidewall) capacity only; any coned grain peaked above the eave adds extra and any sloped floor or hopper subtracts - consult your bin chart for those.

Worked Example

A 24 ft diameter bin filled to a grain depth of 20 ft. Radius = 12 ft, so volume = π × 12² × 20 = π × 144 × 20 ≈ 9,048 cubic feet. Bushels = 9,048 × 0.8036 ≈ 7,271 bushels. Drop the grain depth to 10 ft and the bin holds about half that, 3,635 bushels - capacity scales straight-line with depth but with the square of diameter, which is why a small jump in bin width adds so much storage.

Common Mistakes

Using bin height instead of actual grain depth when estimating what is currently stored.

Measuring outside diameter; the steel wall is thin but you want the inside dimension for grain volume.

Forgetting the coned peak when a bin is overfilled - that heap can add several hundred bushels.

Ignoring a hopper bottom or aeration floor, which reduces usable volume below the sidewall calculation.

Applying the 0.8036 factor to wet grain and treating the result as marketable dry bushels.

Tips & FAQ

Why 0.8036? A struck bushel occupies 1.2445 cubic feet, so each cubic foot holds 1 ÷ 1.2445 ≈ 0.8036 bushels - the figure baked into every grain capacity chart. Does grain type change it? The volume-to-bushel factor is constant, but test weight and moisture affect how many marketable bushels and how much actual weight that volume represents. What about the peak? A full bin usually carries a cone of grain above the eave; add it separately with a cone volume if you need a precise full-bin figure. Should I trust this over my bin chart? The math matches a level cylinder exactly, but your manufacturer's chart accounts for floor slope and hopper geometry, so use both and reconcile. Measure carefully - an inch of diameter error compounds because capacity grows with the square of the radius.

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