Linear motion systems are found in countless machines….precision laser cutting systems, laboratory automation equipment, semiconductor fabrication machines, factory automation, and many others too numerous to list. They range from the relatively simple, such as an inexpensive seat actuator in a passenger vehicle, to a complex multi-axis coordinate system complete with control and drive electronics for precision closed-loop positioning. No matter how simple or complex the system, at the most basic level they all have one thing in common…moving a load through a linear distance in a specific amount of time. One of the most common questions when designing a linear motion system centers on motor technology. Once the technology is chosen, the motor needs to be sized to meet the demands of load acceleration, overcoming friction in the system, and overcoming the effect of gravity, all while maintaining a safe maximum operating temperature. This paper will take an engineer step-by-step through the process of sizing the motor to best meet the application needs.