Enter the load on the screw jack, the pitch of the screw, and the lever-arm radius into the calculator to determine the screw jack force.

Screw Jack Force Formula

The following equation is used to calculate the Screw Jack Force.

Fsj = (L * p ) / (2*pi*R)

  • Where Fsj is the screw jack force (lb)
  • L is the load on the screw jack (lb)
  • p is the pitch of the thread (in)
  • R is the lever arm radius (in)

What is a Screw Jack Force?


A screw jack force is the effort force at the end of the arm or handle of a screw jack that is required to insert a screw into a threaded hole.

How to Calculate Screw Jack Force?

Example Problem:

The following example outlines the steps and information needed to calculate the Screw Jack Force.

First, determine the load reading on the screw jack. In this example, the load on the jack is 4000 lb-f.

Next, determine the pitch of the thread. For this problem, the pitch is .25 in.

Next, determine the lever arm radius. The lever arm is measured to be 7 inches.

Finally, calculate the screw jack force using the formula above:

Fsj = (L * p ) / (2*pi*R)

Fsj = (4000 * .25 ) / (2*3.1415*7)

Fsj = 22.73 lbs