With harvest underway or fast approaching, you may be trying to estimate the number of bushels in a partially filled bin and how much capacity is remaining. 

Round Bins

Use the following calculation to estimate the bushels of grain in a round bin.

Bushels = 0.628 x D² x H

Where:

• D is the diameter of the bin, in feet.
• H is the height of the grain mass in the bin (depth of grain), in feet.
• 0.628 is a conversion constant.

Note: The method described above uses the bin's diameter, while the calculator uses the bin's radius (half the length of the diameter).

Example

1. Calculate the number of bushels of corn in a 30-foot diameter bin with the eave 18 feet above the concrete foundation with the drying floor, 1 foot above the foundation. This would make the maximum grain depth 17 feet when the bin is full.
In this case, to calculate the bushels of grain contained from drying floor to the eave:

• Bushels = 0.628 x D² x H
• Bushels = 0.628 x (30 x 30) x 17
• Bushels = 9,608

2. If you have peaked grain at the top of the bin, the bushels in the peak can be estimated by using a different conversion constant in the equation.

• Bushels = 0.209 x D² x H

Where:

• D is the diameter of the bin, in feet.
• H is the height of the grain peak above the eave, in feet.
• 0.209 is a conversion constant for bushels in a cone-shaped pile of grain that extends to the bin wall.

For example, if the top of the peak is 6 feet above the normal depth of grain in the bin, the volume of the peaked grain is calculated as follows.

• Bushels = 0.209 x D² x H
• Bushels = 0209 x (30 x 30) x 6 = 1,128 bu

Add the totals from example equation 1 and equation 2. Total grain in the bin is 10,736 bushels (9,608 + 1,128)

Rectangular, Flat Storage Buildings

For rectangular flat storage buildings, the math is simpler. Multiply length (ft) by width (ft) by grain depth (ft) by 0.8 bushels per cubic foot.

Let's calculate the amount of grain in a flat storage building that is 40 feet by 60 feet and has a grain depth of 10 feet.

• 40 x 60 x 10 x 0.8 = 19,200 bushels in the bin