Irrigation Water Requirement Advisory Service (IWRAS) has developed a app which will be useful to estimate Etr. The irrigation water requirement of different crop is different and for a specific crop varies over the growth season. The irrigation water requirement for the same crop and soil is different for different regions because of variations in meteorological parameters.The basic information that is required for estimating the irrigation water requirement of the crops is based on parameters like temperature, humidity, sunshine hrs, wind speed etc. The weather data estimates the Etr of crop and crop coefficient values.