Three different scale commercialized spiral wound (SW) type forward osmosis (FO) elements were evaluated. Each element has a unique optimum operating condition, because operating conditions depend on the dimension, performance and element design factor. These factors determine the operating conditions and plant capacity of the SWRO process. This study evaluates the effect of the size in SWFO element via performance evaluation and economic analysis. Moreover, investigation of engineering factors for possible commercialization of SWFO-RO hybrid system was also carried out. Investigation of engineering effect and process economic impact is essential stage for system implication and technology step up. For each element size, maximum FS recovery, DS dilution rates and water flux were highly dependent on the varying design factors. The maximum FS recovery rate were 37.2 and 62.6%; the DS dilution rates were 62.6% for 2540 and 8040 SW, respectively. The water flux for 2540 and 8040 SW elements were 27.6 and 21.1 LMH, respectively Nevertheless, 8040 is 24% more economically than 2540 because of the 8040 can satisfy the minimum requirement of capital cost factors. Nevertheless, 8040 is 24% more economical than 2540 because 8040 can satisfy the minimum requirement of the capital cost factors.