<p>On-demand services are gradually being introduced worldwide. Each city usually provides both fixed-route and on-demand mobility services, improving mobility convenience in city areas. However, the benefits to users cannot easily be estimated. Fixed-route services facilitate understanding of users’ convenience by measuring access times to stations using conventional methods. However, on-demand services, which are usually not mass-transit services, change service quality spatiotemporally. Moreover, mixing the two types makes understanding more challenging. In this study, we propose a multi-mobility service availability rate (<i>MA</i>) that enables us to easily assess the convenience of mobility services, including on-demand services, across subareas. As case studies, we conducted simulations using <i>MA</i> in two areas with different multiple-service situations. In the first case, we evaluated the convenience of multiple mobility services. We selected the best service plan among three candidates based on the equity of <i>MA</i> in each subarea. In the second case, we searched for improvement measures and decided on the improvement direction in the context of an additional on-demand bus service. These findings underscore the value of <i>MA</i> as a practical tool for transportation planners and operators seeking to enhance multi-mobility service environments.</p>