Accurate measurement of limb length and girth is essential in various fields, including health care, sports medicine, and rehabilitation. The developed instrument combines rotary encoders with an Arduino microcontroller and specialized software algorithms, enabling real-time data collection and analysis. This automated approach not only reduces potential errors but also simplifies the measurement process, making it accessible for healthcare practitioners and physical therapists. The study’s findings demonstrate that the instrument achieves the accuracy required for clinical applications and delivers immediate feedback, enhancing the monitoring of rehabilitation progress.