Why Belt Width Matters
Specifying the wrong belt width has real consequences. Too narrow: the belt can't carry the required tonnage, spillage occurs at edges, and material piles in the center. Too wide: capital cost is higher than necessary and the belt may track poorly when lightly loaded.
Belt width selection is a calculation, not a guess. This page explains the key factors and gives practical guidance.
The Two Constraints That Drive Width
Belt width is determined by whichever of these two constraints is binding:
1. Volumetric capacity (tonnage requirement) The belt must be wide enough to carry the required tonnes per hour at the chosen belt speed. A narrower belt needs higher speed to carry the same tonnage β up to a point.
2. Maximum lump size Material with large lump size needs a wide belt to avoid lump spillage and edge damage. There are practical rules for minimum belt width relative to lump size.
Capacity Calculation β Simplified
The carrying capacity of a conveyor belt depends on: - Belt width - Belt speed (m/s) - Trough angle (20Β°, 35Β°, or 45Β°) - Material bulk density (t/mΒ³) - Surcharge angle (how steeply the material piles on the belt)
For a quick estimate, approximate carrying capacities at 1 m/s belt speed and 35Β° trough angle:
| Belt Width | Approximate Capacity at 1 m/s (bulk density ~1.6 t/mΒ³) |
|---|---|
| 500mm | ~90 t/h |
| 650mm | ~150 t/h |
| 800mm | ~240 t/h |
| 1000mm | ~380 t/h |
| 1200mm | ~570 t/h |
| 1400mm | ~780 t/h |
| 1600mm | ~1,020 t/h |
| 1800mm | ~1,300 t/h |
| 2000mm | ~1,600 t/h |
These are approximate figures for planning purposes. Actual capacity depends on your specific material and belt speed. Most conveyors run at 1.5β4 m/s β multiply these figures by your belt speed factor accordingly.
Maximum Lump Size Rules
Rule of thumb: Belt width should be at least 2.5β3Γ the maximum lump size for predominantly lumpy material. For mixed material (mostly fines with some lumps), belt width should be at least 2Γ maximum lump size.
| Maximum Lump Size | Minimum Recommended Belt Width |
|---|---|
| 50mm | 300mm (400mm practical minimum) |
| 100mm | 500mm |
| 150mm | 650mm |
| 200mm | 800mm |
| 300mm | 1000mm |
| 400mm | 1200mm |
| 500mm | 1400mm |
For primary crusher discharge with occasional large lump (say 95% passing 300mm but top size 500mm), use the top size to set the minimum width.
Belt Speed Considerations
Increasing belt speed allows narrower belt width for the same capacity β but speed has limits:
Upper speed limits by material: - Fine, dusty material (coal fines, cement, phosphate): 2.0β3.0 m/s (excessive speed causes dust and spillage) - General bulk ore (iron ore, copper ore, limestone): 3.0β4.5 m/s - Coarse, heavy lump material: 2.5β3.5 m/s (high speed with large lump causes belt damage at loading)
Practical note: A wider, slower belt often outlasts a narrower, faster belt because lower speed reduces wear on belt cover, idlers, and loading zone components. When in doubt, don't push speed to the maximum.
Standard Belt Widths
Belt manufacturers standardize on specific widths. Custom widths are possible but add cost and lead time. Standard widths (mm):
400, 500, 650, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400
When your calculation falls between standard widths, round up to the next standard size.
Common Mistakes in Width Selection
Selecting width based on existing equipment without recalculating. "The old belt was 800mm so we'll use 800mm" ignores whether 800mm actually suits the current production rate. Operations expand over time β what worked originally may be undersized now.
Using maximum capacity without a throughput factor. A belt running at its theoretical maximum capacity continuously is near the edge. Design capacity is typically 80β85% of maximum to allow for surge loading.
Ignoring lump size for fine material conveyors. "We mainly handle fine material" is true until maintenance empties a chute blockage and a large lump goes through. If the crusher occasionally passes oversize, size the belt accordingly.
Over-specifying width to be "safe." Wider belts have higher capital cost, require wider conveyor structure, and may track poorly when running light. Match width to actual requirements.
Frequently Asked Questions
We're replacing an existing belt. Should we use the same width? Check whether the existing width is adequate for current production rates. If the operation has expanded since the conveyor was originally designed, it may be worth increasing width and capacity at the same time.
Our required capacity is between two standard width options. Which do we use? Round up to the next standard width. The cost difference between adjacent standard widths is modest and you gain capacity margin.
Do you need full engineering calculations to order a belt? For a replacement belt on an existing conveyor, you can specify the same width and EP rating as the current belt. For new installations or significant changes, proper belt selection calculations should be done by a conveyor engineer.
Contact Elephant Rubber
We manufacture EP and steel cord conveyor belts in all standard widths from 400mm to 2400mm. Contact us with your required capacity, material type, lump size, and belt speed for a width recommendation.