Pneumatic muscle is a new type of actuator that has a number of advantages over pneumatic cylinders, such as higher power-to-weight ratio, smooth speed adjustment, and longer operating life. Pneumatic muscle-based industrial devices can be used in combustible, explosive, and contaminated environments in different industry fields. This article is dedicated to the modeling of pneumatic muscles manufactured by FESTO, a global leader in the production of this type of pneumatic actuators. The existing pneumatic muscle models have several significant drawbacks: they can only be applied to specific types of pneumatic muscles and are inappropriate for FESTO pneumatic muscles, their accuracy is low, and they contain too many adjusting factors. The model presented in this article makes it possible to obtain static characteristics with up to 10% accuracy. The aim of this study is to assess the feasibility of application of the developed expression for modeling the dynamic characteristics of pneumatic muscle and to develop a comprehensive mathematical model of pneumatic muscle for describing the processes of raising and lowering a load.