Screw Conveyor Calculator

Screw diameter and speed from volumetric capacity.

Design throughput

t/hr

Screw diameter

Bulk density

kg/m³

Conveyor length

Trough fill level

Pitch ratio (pitch/D)

Incline angle

Drive efficiency

Tab to move between fields

Operating RPM

60 RPM

Actual throughput

18.32 t/hr

Required RPM (uncapped)163.7 RPM

CEMA max RPM60 RPM

Volumetric capacity22.9 m³/hr

Incline capacity factor100%

Motor power0.37 kW

Motor power0.5 HP

Shaft torque59.4 N·m

How to Use This Calculator

Enter the required material throughput in cubic feet per hour or tons per hour.
Set screw diameter, pitch, and RPM.
Input material bulk density and trough fill percentage.
Review actual capacity, required horsepower, and shaft torque.
Use the HP and torque values to select motor, gearbox, and coupling specifications.

How the result changes with Screw diameter

Design throughput: Required material flow rate in tonnes per hour.
Screw diameter: Standard sizes: 150, 200, 250, 300, 400, 500, 600, 750, 900 mm.
Bulk density: Material bulk density. Grain ~750, cement ~1500, sand ~1600 kg/m³.
Conveyor length: Total screw conveyor length. Max ~40m with intermediate bearings.
Trough fill level: CEMA Class I (15%), Class II (30%), Class III (45%).
Pitch ratio (pitch/D): Standard pitch = 1.0 (pitch equals diameter). Short pitch = 0.67.
Incline angle: Angle from horizontal. Capacity drops significantly above 15°.
Drive efficiency: Motor and gearbox combined efficiency.

Operating RPM: Screw speed (capped at CEMA max recommended RPM).
Required RPM (uncapped): RPM needed for full throughput (may exceed CEMA limit).
CEMA max RPM: Maximum recommended screw speed per CEMA standards.
Actual throughput: Achievable throughput at operating RPM with incline reduction.
Volumetric capacity: Volume of material conveyed per hour.
Incline capacity factor: Capacity retained due to incline (100% = horizontal).
Motor power: Total required motor power including friction and material lift.
Motor power: Motor power in horsepower.
Shaft torque: Torque at the screw shaft for coupling and bearing selection.

Identify Input Parameters
4 parameters
Design throughput = 50, Screw diameter = 300, Bulk density = 800, Conveyor length = 6 = 8 input(s) provided
Calculate Operating RPM
Operating RPM = min(requiredRpm, maxRpm)
60 = 60
Calculate Actual throughput
Actual throughput = actualMassCapacity * inclineReduction
18.32 = 18.32
Calculate Required RPM
Required RPM = throughput / (volPerRev * 60 * bulkDensityT)
163.7 = 163.7
Calculate CEMA max RPM
CEMA max RPM = round(60 / sqrt(diameterInches / 12))
60 = 60