The Beijing Urban Master Plan and the Communist Party of China’s “Nineteenth National Congress” report both sought to “raise and improve people’s living standards” and “build a high-quality and balanced public service system covering urban and rural areas, as well as to achieve full coverage of the quarter-hour community service circle”. In this study, we propose a calculation method for increasing the service capacity of community public facilities, starting with the quarter-hour community service circle and taking into account factors such as population density, road network walking time, and facility scale. Public facilities have a 15-min service circle model and a capacity calculation model. The proposed method provided results that are both accurate and reasonable. In addition, this study also compares the difference between the actual population size and the service population size for public facilities within a community service circle within a 15-min walk. In addition, the reasons for the disparity were analyzed so that the deficiencies and shortcomings in community public services could be identified, allowing for an accurate assessment of the facility gaps in community public services and the establishment of a solid foundation for further adjusting and optimizing the function settings of the facilities of the community life service industry and the informed construction of a layout of the space of life service facilities to ensure comprehensive coverage.