Get the capacity of a round grain bin or silo in bushels, tons, and cubic feet. Enter the diameter and grain depth, pick how it's filled, and the math is shown below. Free, no signup.
Fill shape
Capacity
11,360bu
Weight
318tons
Cubic feet
14,137ft³
Assumes grain level with the wall at the stated depth. A coned-up peak adds capacity; switch to Peaked to include it.
Cubic yards: 524 · Cubic meters: 400.3 · 1 bu = 1.2445 ft³
A grain bin is a cylinder, so its volume is the floor area times the depth of grain. Measure the inside diameter and the grain depth in feet, then convert cubic feet to bushels by dividing by 1.2445, the cubic feet in one US dry bushel.
Level fill (grain even with the wall):
bushels = (π × r² × depth) ÷ 1.2445, where r = diameter ÷ 2
The same thing as a one-step shortcut for a round bin:
bushels ≈ 0.631 × diameter² × depth (feet)
Peaked and hopper fills add a cone. A cone holds one-third of the cylinder with the same radius and height, so a coned-up peak adds (π × r² × peak height) ÷ 3, and a hopper-bottom silo adds the same term for its cone at the base.
Bushels for grain are a volume, not a weight: the 1.2445-cubic-foot bushel is the same for corn, wheat, and soybeans. Weight comes from test weight, the legal pounds per bushel a grain is graded on (56 for corn, 60 for wheat and soybeans), which moves with moisture. To go from a measured pile of grain outside a bin to tons, our cubic yards to tons converter and stockpile volume calculator handle loose material by density.
The formulas are exact for a perfectly filled bin. Real grain bridges, cones as it fills, and draws down in a funnel, so a struck-full number drifts from what is actually inside, especially near the top and after partial unloads. That is fine for planning storage and freight. When the number feeds a balance sheet, a loan, or a sale, a measured reading is the standard, which is what Rebulk provides for stored bulk.
Find the cylinder volume in cubic feet (π × radius² × grain depth), then divide by 1.2445 to convert cubic feet to bushels. The shortcut for a round bin is bushels ≈ 0.631 × diameter² × depth, with diameter and depth in feet. Add a coned-up peak or a hopper bottom by adding the cone volume, which is one-third of the cylinder formula for the same radius.
One cubic foot holds about 0.804 bushels, because a US dry bushel used for grain storage is 1.2445 cubic feet. So cubic feet ÷ 1.2445 gives bushels, and bushels × 1.2445 gives cubic feet. Corn, wheat, and soybeans all use the same volume bushel; only their weight per bushel differs.
Measure the inside diameter and the depth of grain, pick the fill shape (level, coned-up peak, or hopper bottom), and the calculator applies the cylinder and cone formulas and converts to bushels and tons. For a straight-wall silo with a cone bottom, add the cylinder volume and the cone volume together.
The geometry is exact for a perfectly filled bin, but real fills are not: grain bridges, cones as it fills, and draws down unevenly, so a struck-full estimate can be off by more than you would expect near the top and after partial unloads. For inventory that feeds a balance sheet or a loan, a measured reading beats a calculated one.
Grain bridges, cones, and draws down unevenly, so struck-full is rarely what's really inside. Rebulk measures actual stored volume, per bin and per pile, on one record.
