Pulley Torque Calculator

Force (N):

Drive Pulley Radius (m):

Efficiency of Drive-Belt System (%):

Torque (Nm):


About Pulley Torque Calculator (Formula)

A Pulley Torque Calculator is an essential tool used in mechanical engineering and design to determine the torque required or generated in a pulley system. Pulleys are simple machines that consist of a wheel with a groove around its circumference and a belt or cable that runs inside the groove. They are commonly used to transmit rotational motion and mechanical power in various applications, such as lifting heavy loads, driving conveyor belts, and transmitting power in engines. Calculating the torque in a pulley system is crucial for designing and optimizing mechanical systems. Here, we’ll delve into the concept of pulley torque and provide the formula used in pulley torque calculations.

Understanding Pulley Torque: In a pulley system, torque is the rotational force applied to the pulley to make it turn. It is typically measured in units like Newton-meters (Nm) or foot-pounds (lb-ft). The torque in a pulley system depends on several factors, including the force applied to the pulley (tension in the belt or cable), the radius of the pulley, and the coefficient of friction between the belt and the pulley.

Formula for Pulley Torque Calculation: The formula for calculating the torque in a pulley system is as follows:

Torque (T) = Tension in Belt (F) × Radius of Pulley (r)


  • Torque (T) is the rotational force or torque applied to the pulley, measured in Newton-meters (Nm) or foot-pounds (lb-ft).
  • Tension in Belt (F) represents the force applied to the belt or cable, which is often due to the weight of an object being lifted or the power transmitted. It is measured in Newtons (N) or pounds-force (lbf).
  • Radius of Pulley (r) is the distance from the center of the pulley to the point where the tension is applied. It is measured in meters (m) or feet (ft).

The torque in a pulley system depends on the tension in the belt or cable and the radius of the pulley. Increasing either the tension or the pulley’s radius will result in higher torque requirements or torque output, depending on the specific application.

Applications of Pulley Torque Calculations: Pulley torque calculations are essential in various engineering applications, including:

  1. Lifting Systems: Determining the torque required to lift heavy loads using pulley systems, such as cranes and elevators.
  2. Power Transmission: Calculating the torque needed to drive conveyor belts, industrial machinery, and automotive engines through pulley systems.
  3. Design and Optimization: Designing pulley systems for optimal performance and efficiency while minimizing wear and tear.
  4. Mechanical Analysis: Evaluating the mechanical properties of pulley systems to ensure they meet safety and performance standards.

In conclusion, a Pulley Torque Calculator is a valuable tool for engineers and designers working with pulley systems. It aids in the design, analysis, and optimization of mechanical systems involving pulleys, ensuring they operate efficiently and effectively in various applications.