To effectively predict the hourly capacity of the airport terminal area, i.e., to measure the maximum number of aircraft that can receive air traffic services in a sector simultaneously under the condition that the capacity is known, this study proposes a model to calculate the terminal area capacity based on the perspective of service resources. Firstly, the supply and demand relationship between the terminal area capacity and service resource consumption was analyzed based on the configuration of the terminal area route network, traffic flow characteristics and airspace safety, and security capacity requirements. Secondly, by defining a flight service probability matrix, a demand service time model and a maximum available service time model for the terminal area were developed. Based on the balance between the supply and demand of service resources, a model was constructed to forecast the capacity of the terminal area. Finally, the validity of the model was verified by simulation. The example results indicated that the difference between the limit and correction capacities obtained from the model calculations and the simulation results is lesser than 0.3 vehicles/hour. Both the results are consistent with the actual operation, thus proving the validity and reliability of the calculation model used in this study. It was also found that when the capacity is known, the model can calculate the maximum number of aircraft receiving services simultaneously within the terminal area at peak times. These findings suggest that the proposed model can provide a theoretical basis and reference for terminal area sectoring and traffic alerting.