Physiotherapists frequently use ultrasound machines for the treatment of chronic inflammation, degenerative rheumatic disorders, ankle distortions, and post-traumatic diseases, such as lateral epicondylitis and acute soft tissue injuries [1]. At a low power of less than three-watts, ultrasound effects could produce stable cavitation in biological tissues, which in turn could affect the permeability of cell membranes. At high power settings up to twelve-watts, the absorption of ultrasound energy by tissues causes a temperature increase, which causes an increase in the blood flow. To ensure safe and effective treatments, it is important that the adopted ultrasound therapy devices are accurate. In general, the use of uncalibrated systems could produce treatments that are inefficient or even harmful to patients [2]. In this context, the objective of this work was to evaluate the performance of ultrasound devices that are commonly used in physical therapy departments [3].