Why motor torque matters
Motor torque shows turning force at the shaft. It links power, speed, load radius, and gearing. A motor may have enough rated power, yet still fail during starting. That happens when starting torque, service factor, or gearbox loss is ignored. This calculator combines those items in one workflow. It supports design checks for conveyors, pumps, mixers, winches, fans, and small machines.
Practical design checks
Start with the rated output power and speed. The calculator converts them into shaft torque. Then enter the load force and lever radius. This gives the torque demanded by the driven load. Add a service factor for shock, dust, heat, frequent starts, or uncertain data. A higher factor gives safer selection, but it can increase motor size.
Gear ratio changes torque and speed together. A reduction gearbox raises output torque. It also lowers output speed. Real gearboxes waste energy, so transmission efficiency is included. The required motor torque is divided by both gear ratio and efficiency. This helps compare the motor shaft with the load side.
Electrical estimates
The electrical section estimates input power from voltage, current, phase, and power factor. Efficiency converts that input into mechanical output. This is useful when nameplate power is missing, or when field readings are taken with a meter. The result should be treated as an estimate. Meter accuracy and operating conditions affect it.
Using the results
Compare available output torque with required load torque. Check the margin value. A positive margin means the design has reserve torque. A low margin means the motor may run hot, trip, or stall. Review acceleration loads separately when the machine has heavy inertia. Also compare calculated current torque from the torque constant when using servo or direct current motors.
Use consistent units and realistic assumptions. Measure radius at the point where force acts. Use running speed, not no load speed, for loaded torque. Keep efficiency values conservative. Save the exported report with the project file. It records assumptions and helps later maintenance decisions.
Safety note
For brakes, lifts, cranes, and hoists, use approved standards. Confirm torque with manufacturer data. Add guards and overload protection. Field testing should be supervised by qualified people. Document every final setting before startup carefully.