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Stockpile and silo capacity

Pick the material and storage shape to see how many tons fit, how much yard the pile takes and how many days of consumption it covers.

Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.

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Material
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Consumption

Conveying hours set the belt or screw rate that feeds or reclaims this storage.

—Storage capacity
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Storage profile

Section with the calculated dimensions. Elongated pile: side view. Horizontal and vertical scales may differ.

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Capacity versus height

Stored mass as pile height or cylinder height changes, everything else fixed.

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Material table

Typical bulk density and angles within CEMA ranges (Belt Conveyors for Bulk Materials, Table 3-3). The highlighted row is the selected material.

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Method, assumptions and references

Equations used

Conical pile: R = H ÷ tan θ; V = π · R² · H ÷ 3; footprint = π · R²
Elongated pile: B = 2 · H ÷ tan θ; straight section Ls = L − B; V = (B · H ÷ 2) · Ls + π · (B/2)² · H ÷ 3; footprint = B · Ls + π · (B/2)²
Silo: Hh = (D − d0) ÷ 2 · tan α; V_hopper = π · Hh ÷ 12 · (D² + D · d0 + d0²); V_cylinder = π · D² ÷ 4 · Hc; V_cone = π · D² · (D/2 · tan θ) ÷ 12
Mass = V · ρ_bulk; autonomy = mass ÷ daily consumption; conveying rate = consumption ÷ operating hours

Assumptions and limits

  • Straight slopes at the angle of repose and a flat floor; real piles built by stackers or trucks are irregular and surveyed volumes can differ by 5% to 15%.
  • Constant bulk density: compaction with height and moisture changes are not included. Table values are typical within CEMA ranges; use data for your own material.
  • Silo: geometric volume with center filling. Wall pressures, structural loads and the mass-flow hopper angle need specific design (EN 1991-4, ACI 313, Jenike method).

Standards and technical documents

  • CEMA: Belt Conveyors for Bulk Materials, 7th ed. (2014), Table 3-3 (material characteristics)
  • CEMA Standard 550: Classification and Definitions of Bulk Materials
  • EN 1991-4:2006 (Eurocode 1, Part 4): Silos and tanks
  • Jenike, A. W.: Storage and Flow of Solids, Bulletin 123, University of Utah, 1964
  • Schulze, D.: Powders and Bulk Solids — Behavior, Characterization, Storage and Flow, Springer, 2008

U.S. regulations

  • OSHA 29 CFR 1910.272: grain handling facilities
  • OSHA 29 CFR 1910.146: permit-required confined spaces
  • OSHA 29 CFR 1926.250: general requirements for storage
  • ACI 313: Design specification for concrete silos and stacking tubes for storing granular materials

Frequently asked questions

How do I calculate the volume of a conical stockpile?

Base radius is height divided by the tangent of the angle of repose, and volume is π × radius² × height ÷ 3. A 30 ft limestone pile at 38° has a 38.4 ft radius and about 46,300 ft³, or roughly 2,000 short tons at 87 lb/ft³: eight days at 250 short tons per day.

Does an elongated pile hold more than a conical one?

For the same height, yes: each foot of straight section adds B × H ÷ 2 of volume. At 30 ft high and 38°, that is about 1,150 ft³ per foot, and the yard is used better.

What hopper angle should a silo have?

For flow without dead zones, walls are usually 60° to 70° from horizontal, or steeper for cohesive materials. Below the angle of repose plus 15°, flow tends to be funnel flow. The exact angle comes from shear testing with the Jenike method.

Where do I find bulk density and angle of repose?

The CEMA table gives typical ranges, but moisture and particle size change the values a lot. For design, weigh a container of known volume for bulk density and let the material form a cone to measure the angle of repose.