Lead Screw Torque Calculator

About this calculator

A lead screw converts rotational motion into linear motion, and the torque needed to drive it is calculated from the axial load, the screw’s lead (the linear distance traveled per revolution), and the mechanical efficiency of the thread — typically 20 to 40% for common Acme or trapezoidal threads because of friction between the screw and nut, versus 90%+ for a ball screw with rolling elements. The general relationship is T = (F × L) ÷ (2π × η), where F is the axial force, L is the lead, and η is efficiency.

Mechanical and mechatronics engineers use this calculation to size stepper or servo motors for CNC machines, 3D printers, linear actuators, and jack screws, since undersizing the motor means it stalls under load while oversizing wastes cost and power. It’s a standard step in the design of any linear-motion system built around threaded rod rather than a belt or ball screw.

This calculator takes your axial load, screw lead, and thread efficiency and returns the torque required to drive the load.