Grain Bin Calculator
Calculate grain bin capacity in bushels from bin diameter and eave height. Supports corn, soybeans, wheat and more. Includes peaked grain surface, test weight conversion and grain value estimate.
Grain Bin Calculator Tool
Why use this free grain bin calculator?
Built with the features most competitors miss — from benchmark comparisons to multi-method inputs and actionable guidance.
How to use this grain bin calculator
Common grain bin sizes and capacities (corn, flat)
| Diameter x Eave height | Capacity (flat) | Capacity (peaked) | Corn weight |
|---|---|---|---|
| 18 ft x 14 ft | ~2,620 bu | ~2,930 bu | ~73,000 lbs / 37 tons |
| 24 ft x 16 ft | ~5,890 bu | ~6,600 bu | ~165,000 lbs / 82 tons |
| 30 ft x 18 ft | ~10,230 bu | ~11,460 bu | ~286,000 lbs / 143 tons |
| 36 ft x 18 ft | ~14,730 bu | ~16,500 bu | ~413,000 lbs / 206 tons |
| 42 ft x 20 ft | ~22,300 bu | ~24,980 bu | ~625,000 lbs / 312 tons |
| 48 ft x 22 ft | ~31,000 bu | ~34,720 bu | ~868,000 lbs / 434 tons |
How this calculator compares
LazyTools fills the gaps most competing tools leave open — deeper analysis, benchmark context, and actionable guidance alongside the core calculation.
| Feature | LazyTools | OmniCalculator | GrainNet.com | Sukup.com |
|---|---|---|---|---|
| Bushels from diameter + height | ✓ Yes | ✓ | ✓ | Partial |
| 8 grain types with test weights | ✓ Yes | ✗ | ✗ | ✗ |
| Peaked surface calculation | ✓ Yes | ✗ | ✗ | ✗ |
| Grain value estimate | ✓ Yes | ✗ | ✗ | ✗ |
| Weight in lbs and tons | ✓ Yes | Partial | ✗ | ✗ |
| Hopper-bottom bin option | ✓ Yes | ✗ | ✗ | ✗ |
Grain Bin Calculator: Complete Guide
Knowing your grain bin capacity accurately is essential for harvest planning, grain marketing, insurance documentation, and loan collateral. This calculator gives precise bushel capacity figures from the key measurements of any round grain bin.
Grain bin geometry: cylinders and cones
A round grain bin consists of two geometric shapes: a cylinder (the sidewall section below the eave) and, when grain is peaked, a cone on top. Cylinder volume = pi x radius squared x height. Peak cone volume = (1/3) x pi x radius squared x cone height. Total capacity is the sum of both volumes converted from cubic feet to bushels using the grain test weight: Bushels = Cubic feet x (test weight / 62.4).
Test weights and the bushel conversion
Different grains have different densities expressed as test weight in lbs per bushel. Standard US test weights: corn 56, soybeans 60, wheat 60, barley 48, oats 32, sorghum 56, sunflower 25, canola 50 lbs/bu. The conversion factor 62.4 is the weight of one cubic foot of water. Test weight as a fraction of water density gives the volume-to-bushel conversion factor.
Peaked vs flat vs hopper-bottom surface profiles
A flat surface (grain levelled to the eave) holds the least grain. A natural peaked surface (the cone that forms during auger loading) adds approximately 10 to 15% above the cylinder volume. Hopper-bottom bins have a funnel-shaped floor that reduces usable capacity by approximately 15% compared to a flat-floor bin of the same diameter and eave height. Select the correct profile for accurate capacity estimates.
Grain value estimation for insurance and marketing
Entering current market price per bushel gives an estimated total grain value for insurance documentation, bank collateral, or sale planning. Farm insurers and agricultural lenders often require documented storage capacity as part of crop insurance and farm operating loan assessments. Having accurate bin capacity figures helps ensure your coverage and collateral assessments are accurate.
Structural loading: weight per bin
Grain weight is important for structural planning. A 36-ft diameter bin with 18-ft eave filled with corn weighs approximately 412,000 lbs (206 short tons). Bin manufacturers specify load ratings per square foot of floor area. Old bins or bins on soft ground should be assessed by a structural engineer or bin manufacturer before filling to maximum capacity.
Common grain bin sizes and their capacities
The most common commercial grain bins in the US range from 18 to 48 feet in diameter with eave heights from 12 to 30 feet. A 30-ft bin with 18-ft eave holds approximately 10,000 bu of corn flat. A 48-ft bin with 22-ft eave holds approximately 31,000 bu flat. Multiple bins at different sizes allow grain segregation by type, moisture, or grade — important for maximising market flexibility and storage management.