The goal of this study is to develop a method for assessing social equity impacts of distance-based public transit fares. According to federal law, disparities must be evaluated by the transit agency, but the techniques identified by the Federal Transit Authority fail to account for disparities in distances travelled by transit users. This means that transit agencies lack guidelines for assessing the social equity impacts of replacing flat fare with distance-based fare structures. Our solution is to incorporate a model of trip generation and distance travelled into a GIS System, which enables a planner to visualize and compare transit-cost maps. We apply the method to a case study in the Wasatch Front, Utah, where the Utah Transit Authority is exploring a switch to distance-based fares. The analysis reveals that overall distance-based fares benefit low-income, elderly, and non-white populations. However, the effect is geographically uneven, and may change depending on where members of these groups live.