We have studied a mathematical model to compare the handle of polylactic acid (PLA) and polyethylene terephthalate (PET) fabrics throughout finishing steps. Mechanical and surface properties at low stress of PLA and PET fabrics and the effects of different finishing treatments on these properties are investigated. The KES-FB (Kawabata Evaluation System for Fabrics) is used for the measurements of low stress tensile, shear, bending, compression and surface properties. There is no standard method to determine the total handle value for summer knitted fabrics. Therefore a mathematical method i.e. the Weighted Euclidean Distance method was used to indirect determination of total handle value from the KES-system parameters. The results reveal that the mechanical and surface properties as well as handle of PLA and PET fabrics change significantly after different finishing stages. The difference between handle of PLA and PET fabrics has been significantly reduced after dyeing, drying, heat setting and softening processes.