The underground parking fires pose a serious risk to safe egress due to rapid smoke accumulation. Therefore, the proper design of ventilation and smoke-control systems to preserve visibility and facilitate emergency evacuation is of critical importance. Nonetheless, the minimum air volume required to establish an adequate visibility for safe egress, as specified by international standards, has various interpretations. In this study, using PyroSim software, the required ventilation air change rate for smoke exhaustion from a 4 MW fire that remains active for 5 minutes was numerically analyzed in four enclosed parking areas with floor areas of 500, 1000, 1500, and 2000 m². The visibility status was evaluated ten minutes after the onset of the fire. Results indicate that for the 500 and 1000 m² parking areas, achieving a visibility of 10 m within ten minutes after ignition requires an air-change rate of 25 air changes per hour (ACH). In contrast, larger parking areas with floor areas of 1500 and 2000 m² achieve the same visibility with an air-change rate of 20 ACH at all points in the parking facility. This difference is attributed to more uniform airflow distribution and better smoke dispersion in larger spaces.