The capacity of modern computer numeric control (CNC) machine tool builds on the machine design (structural rigidity, drive system, control looping, etc.), machining process (cutting speed, feed rate and cutting forces) and environment (temperature and vibrations).The linear drive system of CNC machines consists of ball screw and its associated components. The servomotor drives the feed drive system in control conditions at required speed, and providing feedback to controller of the machine. Feed drive system is responsible for the performance of linear axis of machine. The performance indicators include positioning accuracy, repeatability and backlash. The required accuracy on workpiece relies on the torque/power of axis motors. The objective of this article is to derive an equation for the computation of torque for the feed drive system of CNC machines. We have proposed two simple and easiest method of computing torque. Firstly, we computed the torque required for the running of linear axis of machine under load conditions by the first method. Secondly, the verification of computed torque has been done by the second method. Thirdly, we have analyzed three major factors like rapid rate, weight over the system and lead of ball screw to study the behavior of torque. Finally, analytical estimations have been carried out for the validation of the deployed method.