Heart Rate (HR) monitors have become pervasive tools, with a great impact on fitness as well as on healthcare. The development of smart wearable systems to monitor physiological parameters addresses the need to manage real-time data for both personal and medical needs. Therefore, it is fundamental to assess and improve the reliability of these devices in HR measurement. The objective of this study was to evaluate the overall performance of a commercial chest-strap HR monitor and perform a calibration procedure. A DAQ-based system was developed to acquire and process raw signals from the sensor. When tested using a highly stable generated ECG signal, the device showed very small measurements errors with low standard deviation, granting high accuracy and good performance that improved even more after calibrating it.