Evapotranspiration calculations are essential in quantifying available water, hydrological modelling, monitoring, and planning for drought occurrence and predicting its indices. Where observations are sparse and data quality is questionable; the need for simplified algorithm is urged. Thirteen models were used to calculate potential evapotranspiration (ETp) on daily and monthly time series meteorological data in Central Jordan-Amman City. Temperature-based, Class A-Pan evaporation (1970-2013), and solar radiation-based methods (1986-1999) were elaborated to estimate the reference ET. Evaluation and benchmarking were performed based on regression algorithm of linearity assumption against the climate models ETs projections of CMIP5-RCP 2.6, CLM-ERAi, Penman Monteith ERA Interim, and Priestley Taylor ERA-CLM. All methods to estimate ET ratify significant trends to the state of local climate. The analysis showed asymmetry between both CMIP5-RCP 2.6 and CLM-ERAi outputs and calculated ETs but inconsistent with Penman Monteith ERA Interim and Priestley Taylor ERA-CLM. Penman Monteith ERA-Interim demonstrates the literature values that vary from 51 to 280 mm/month. Blaney Criddle and Hargreaves temperature and solar based formulas prototyped the potential evapotranspiration (R2= 0.99-0.97) followed by Makkink and Jensen-Haise radiation-based formulas (R2= 0.97-0.96). The remaining models need to be calibrated under the local conditions due to its limitation in the current constants.