Evaporation demand or potential evaporation is projected to increase almost everywhere in the world in future climate scenarios. Estimation of evapotranspiration (ET) is important for determining the agro-climatic potential of a particular region, water requirements of field crops, irrigation scheduling, and suitability of crops or varieties, which can be grown successfully with the best economic returns therefore numerous models have been developed for determining evapotranspiration. The present study was taken for Jorhat, Assam with the main objective of the present study is to highlight the governing equations for infiltration and compare three temperature-based methods for determining reference evapotranspiration namely Thornthwaite, Blaney-Criddle, and Ivanov method. The results obtained from the methods were compared with the evapotranspiration data measured using the class A pan. The interrelationship between the class A pan data and the other reference evapotranspiration method is also determined in the study. Moreover, the result obtained shows that the average monthly ET estimated by Blaney-Criddle, Thornthwaite, and Ivanov methods are 1.57, 3.05, and 2.62 mm/month. The correlation coefficient result shows that all the three methods compared well with the observed pan evaporation. the results of this investigation suggest that the Blaney-Criddle is the better method as compared to the Thornthwaite and Ivanov methods under climatic conditions of Jorhat. Furthermore, the engineering properties of soil collected from the study area were determined and presented in this study.