This paper focuses on the assessment of whiteness indices (WI) changes that occurred in white polyester fabrics according to different fabric layers. Yellowness indices (YI) were also assessed with the WI of fabric samples. White polyester fabrics having different constructional parameters were used, the results showed that WI of polyester fabrics increased up to a certain layer of fabric depending on constructional parameters and compactness of fabric. After a certain layer, WI of fabrics remained almost constant or steeply decreased. YI changed in good relation with whiteness changes. The results showed that the suitable number of fabric layer could be determined for WI measurements according to the compactness and to the structural parameters of the fabric samples. The suitable choice of the fabric layers for whiteness measurement depended on fabric constructional properties and could be made by considering the certain layer number, which could be obtained at the point of the maximum value of whiteness.