Grain Bin Calculator: Bushels in a Round Bin

This calculator estimates how many bushels a round grain bin holds. Enter the bin diameter and the depth of grain when it is levelled; you get the volume in cubic feet and the bushels, using 1.2445 cubic feet per bushel.

Formula

Volume (ft³) = π × (diameter ÷ 2)² × depth. Bushels = volume ÷ 1.2445 (one level US bushel is 2,150.42 in³, about 1.2445 ft³, as defined by USDA/NIST).

• dia: inside diameter in feet
• h: depth of levelled grain in feet

Worked Example

A 30 ft bin with grain levelled at 20 ft.

1. Radius = 15 ft, area = π × 15² = 706.86 ft²
2. Volume = 706.86 × 20 = 14,137 ft³
3. Bushels = 14,137 ÷ 1.2445 = 11,360 bu

How to read the result

This is the volume in level bushels. For a peaked load, add the cone: π r² × peak height ÷ 3. To estimate weight, multiply bushels by the test weight of the crop (for example about 56 lb for shelled corn at standard moisture).

Limits and common mistakes

• Grain packs down in tall bins, so the real amount can be a few percent more.
• Do not enter a bin to measure grain; flowing grain can trap a person. Measure from outside or with a sensor.

Frequently Asked Questions

How many cubic feet in a bushel?

About 1.2445 ft³.

How many bushels in a 30 ft bin per foot of grain?

About 568 bu per foot.

How do I add the peak?

Add π r² × peak height ÷ 3 to the cubic feet.

How do I get tons?

Bushels × test weight (lb/bu) ÷ 2,000.

in dia | Bin diameter | ft | 30 | 0 | 500
in h | Level grain depth | ft | 20 | 0 | 300
out bu | Grain in the bin | bu | pi * (dia / 2)^2 * h / 1.2445 | 0
out ft3 | Grain volume | ft³ | pi * (dia / 2)^2 * h | 0