The regional transportation planning process in the United States has not been easily opened to public oversight even after strengthened requirements for public participation and civil rights considerations. In the effort to improve the public review of regional transportation plans, this paper describes the construction of a proof-of concept web-based tool designed to analyze the effects of regional transportation plans on accessibility to jobs and other essential destinations. The tool allows the user to analyze disparities in accessibility outcomes by demographic group, specifically income and race, as required by civil rights-related planning directives. The tool makes cumulative-opportunity measures of the number of essential destinations reachable within certain times by public transit and automobile. The tool is constructed to analyze the San Francisco Bay Area’s 2005 regional transportation plan. Users can choose to make measures for a particular neighborhood or for all neighborhoods in the region with certain demographic characteristics. Two example analyses are shown with an interpretation and discussion of calculator outputs.