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CONVEYOR BELT CAPACITY CALCULATOR

Material capacity from cross-section, speed, and density

Compute the mass throughput Q (t/h) of a troughed belt conveyor from its width, speed, the material's bulk density, trough angle and surcharge angle. Uses the CEMA equivalent-area method with the standard 3-roll equal-length trough geometry.

Units

Belt

Material

Capacity
Cross-section A
0.1294
m²
1.393 ft²
Volumetric flow
931.8
m³/h
1218.8 yd³/h
Mass throughput
1491.0
t/h
1643.5 stph
Formulas
  • b = 0.9·B − 0.05 m (effective belt width with CEMA edge clearance)
  • L = b / 3, A_trough = L² · sin α · (1 + cos α)
  • A_surcharge = (L · (1 + 2·cos α))² · tan β / 4
  • Q = (A_trough + A_surcharge) · v · ρ · 3600

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How belt capacity is computed

A loaded conveyor belt carries material in two stacked regions: the troughed lower section formed by the carrier idlers (the cross-section below the level of the side roll tops) and the surcharge pile sitting above. The total cross-sectional area A is the sum of the trough area and the triangular surcharge area, both functions of the effective belt width b.

Effective belt width b applies a CEMA standard edge clearance — typically 0.9·B − 50 mm — so the calculation is conservative against material spillage. Each of the three idler segments has length b/3.

Mass throughput Q is volumetric flow (cross-section × speed) multiplied by bulk density and 3600 s/h: Q [t/h] = A [m²] · v [m/s] · ρ [t/m³] · 3600. This is the steady-state capacity at uniform feed; intermittent feed or skirt restrictions can lower the practical maximum by 10–20 %.

Bulk density and surcharge angle reference

Indicative values from CEMA, FEM 2.121, and field practice. Always verify with the actual material — moisture content and lump size can shift density by ±20 %.

MaterialBulk densitySurchargeMax trough
Anthracite coal, sized0.96 t/m³25°30°
Bituminous coal, run of mine0.85 t/m³22°35°
Iron ore, crushed2.50 t/m³20°30°
Limestone, crushed1.60 t/m³22°35°
Sand, dry loose1.60 t/m³18°30°
Sand, wet packed2.00 t/m³10°30°
Gravel, washed and dry1.70 t/m³20°30°
Cement, Portland1.40 t/m³15°20°
Clinker, cement1.40 t/m³22°30°
Bauxite, crushed1.30 t/m³20°30°
Phosphate rock1.20 t/m³22°30°
Wheat0.77 t/m³12°20°
Corn, shelled0.72 t/m³10°20°
Wood chips, hardwood0.40 t/m³30°35°
Salt, rock1.40 t/m³22°30°

Common pitfalls

  • Using catalogue density without verifying moisture content. Wet limestone can be 2.4 t/m³ vs 1.6 t/m³ dry — a 50 % difference in capacity from the same belt.
  • Setting surcharge angle equal to the angle of repose. Surcharge angle is typically 5–10° lower than the static angle of repose because the belt is moving.
  • Picking trough angle without checking belt-edge stress. Steeper troughs (35°, 45°) raise capacity but increase belt curvature stress; consult belt strength tables.
  • Forgetting that capacity scales roughly with cross-section squared, but inversely with material lump size — large lumps need wider belts at the same capacity to avoid centring problems.
  • Mixing imperial density (lb/ft³) with metric belt width — common error when adopting CEMA US sources for a metric design.

When to consult an engineer

This calculator returns the steady-state CEMA equivalent-area capacity for an idealised 3-roll equal-length trough. Real installations face skirt restrictions, non-uniform feed, edge stress limits, and material-specific cleaning requirements. For new conveyor sizing, capacity upgrades, or any installation handling abrasive, high-temperature, or sticky materials, talk to a BisonConvey engineer.

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