This report details the development of a Web-based economic impact calculator for Minnesota's Small and Medium Size, General Aviation airports. In this case, "economic impact" is defined as the result of expenditures or sales transactions between businesses or other entities that can be directly traced to the presence of an airport. The process involved site visits to 51 airports, meetings with airport managers, Fixed Base Operators (FBO), and Metropolitan council officials, as well as data collection of financials from airport sponsors and FBOs. After testing on the calculator was completed, it was transferred to the Mn/DOT Aeronautics server and can be found at http://dotapp1.dot.state.mn.us:8080/aeic/main.htm. We recommend, however, that a new effort be considered to obtain more detailed financials for FBOs as a way to improve calculator accuracy. Although the current model provides a good estimation of FBO expenditures, greater accuracy could be obtained with more data.