Recent interest in using modern roundabouts as an effective and safe method for intersection control in the United States stresses the need for accurate modeling tools. The objective of this paper is to assess the calibration potential of common analytical and microsimulation roundabout models to replicate operations at modern roundabouts. The models considered were aaSIDRA and RODEL (on the analytical side) and PARAMICS, SimTraffic, and VISSIM (on the microsimulation side). For this study, two modern roundabouts from New Hampshire were selected and videotaped during peak-hour conditions. The models’ approach delay outputs were compared with the measured field delay from the videotapes. Model calibration parameters were systematically changed to assess their impact on the results with respect to field observations. Among the conclusions of the study are that current roundabout analysis models vary in regard to the calibration options, that calibration can have a significant impact on improving the models’ results, and that calibration might be site specific.