In this project, all relevant publications available since the completion of the previous PRCI recalibration research efforts (5 years) that address the stability of ultrasonic meters and the results of recalibration were reviewed. The review concentrates on the use of ultrasonic meter diagnostics as a guideline for the need for recalibration rather than time in service. This study includes subsequent recalibration data and a questionnaire to indicate if users of ultrasonic meters have utilized ultrasonic meter diagnostics to determine the need for recalibration.