Planning and design of stormwater facilities (including best management practices and low impact development) involve the calculation of peak flows and runoff volumes. Rainfall-runoff models are frequently utilized to estimate this information. A userriendly rainfall-runoff tool (LIDIA) was developed using Visual Basic for Applications in Microsoft Office Excel. This research showed comprehensive guidelines on how to setup a model in LIDIA and reported the first evaluation of LIDIA using field data. LIDIA hydrologic module was tested using 10-minute rainfall, land cover, soil series, land cover management, and runoff data from two small watersheds in North Mississippi. Eleven storm events, over a period of seven months were used for the one evaluation site and 11 storm events were used for the second case study. Overall the development and results of LIDIA tool showed in this study are positive in keeping the enhancement of the model.