The Rainfall Erosivity Factor (R) refers to the capacity of the rain to produce erosion. Rainfall leads to further ground dislocation and water running off the surface. The Rainfall Erosivity Factor (R) measures the erosive potential of rainstorms and quantifies the amount and rate of runoff that accompanies the rain. The Rainfall Erosivity Factor (R) is of high significance as precipitation drives erosion and directly affects the separation of the soil particles. The erosive force depends on the kinetic energy of the raindrop and the intensity of precipitation for the selected location. The app calculates the R-factor using the formula developed by Wischmeier and Smith (1978) that uses Monthly (Pi) and Annual (P) Rainfall Data. These are retrieved from GIS to compute the Rainfall erositivity factor (R), which is expressed in MJ mm ha−1 h−1 year−1, corresponding to the long-term yearly average of the impact of the kinetic energy of rainfall. The Rainfall Erosivity Factor (R) is used in the RUSLE and the Universal Soil Loss Equation (USLE).