Population growth in Silchar has necessitated the development of efficient transportation systems to alleviate traffic congestion and enhance mobility. This research project focuses on the capacity and level of service (LOS) estimation of a critical roundabout in the city, which is crucial for regulating traffic flow and ensuring smooth vehicular movement. The study aims to evaluate the roundabout’s capacity and LOS to identify areas for improvement and optimization. A comprehensive analysis was conducted using field observations and traffic engineering methodologies, including Indo-HCM 2017, IRC: 65–1976, and Highway Capacity Manual (HCM) 2010 guidelines. Capacity and LOS estimation involved calculating critical gaps and clearance times between minor and major road vehicles using the INAFOGA and clearance time methods for the Indo-HCM method. The IRC method estimated roundabout capacity based on weaving traffic proportions, while HCM 2010 used average control delay. Findings indicate that the roundabout’s capacity, as estimated by Indo-HCM, is 2414 PCU/h with a corresponding LOS B, reflecting efficient functionality with moderate delays. IRC: 65–1976 methodology suggests a capacity of 2884 PCU/h, essential for effective traffic flow. HCM 2010 analysis shows varying capacities for different approaches varying between 792 PCU/hr and 977 PCU/hr, with LOS of C, A, B, and A for four approaches. The outcomes are expected to guide urban planners, traffic engineers, and policymakers in making informed decisions to enhance the transportation network of Silchar, contributing to the city’s sustainable development. Integrating three methodologies enhances accuracy and reliability in transportation planning and traffic management.