Enter the helix angle (deg) and the coefficient of friction into the calculator to determine the Lead Screw Efficiency. 

Lead Screw Efficiency Formula

The following formula is used to calculate the Lead Screw Efficiency. 

Elead = tan(ha) / (tan(ha + arctan (f))) *100
  • Where Elead is the Lead Screw Efficiency (%)
  • ha is the helix angle (deg) 
  • f is the coefficient of friction 

How to Calculate Lead Screw Efficiency?

The following two example problems outline how to calculate the Lead Screw Efficiency.

Example Problem #1:

  1. First, determine the helix angle (deg). In this example, the helix angle (deg) is given as 50.
  2. Next, determine the coefficient of friction. For this problem, the coefficient of friction is given as .65.
  3. Finally, calculate the Lead Screw Efficiency using the equation above: 

Elead = tan(ha) / (tan(ha + arctan (f)))

Inserting the values from above and solving the equation: 

Elead = tan(50deg) / (tan(50/57.2958 + arctan (.65))) = 14.5 (%)


What is a helix angle and why is it important in calculating lead screw efficiency?

The helix angle is the angle between the helical thread of the screw and the screw’s axis. It is crucial in calculating lead screw efficiency because it directly affects the friction and, consequently, the efficiency of the screw’s motion. A larger helix angle can reduce friction and increase efficiency.

How does the coefficient of friction affect lead screw efficiency?

The coefficient of friction represents the amount of resistance encountered when one surface slides over another. In the context of lead screws, a higher coefficient of friction means more resistance between the screw threads and the nut, leading to lower efficiency. Conversely, a lower coefficient of friction means less resistance and higher efficiency.

Can lead screw efficiency exceed 100%?

No, lead screw efficiency cannot exceed 100%. Efficiency over 100% would imply that the system produces more energy than it consumes, which violates the principle of conservation of energy. In practical terms, efficiencies will always be less than 100% due to inherent losses like friction.