Heat transfer through fabrics can be influenced by several factors, such as fiber thermal conductivity, fiber and entrapped air volume fractions, fiber material orientation , and the fabric’s structural pattern . From previous studies, it can be inferred that all the fabric samples have been thermally investigated while they have been in the relaxed condition with no extension. However, in some application, the knitted fabric is in complete contact with the human body and takes the geometrical shape of the conta ct area. Due to their high shape - ability with the body, weft -knitted fabrics should also be considered to have non- uniform deformation corresponding to their contact area. This leads to a non- uni form extension of the fabric. This non- uniform extension would change the geometry of the fabric, ultimately affecting heat transfer properties. In this study plain single jersey, plain rib and interlock knitted structures were fabricated using an electronic flat knitting machine , in order to investiga te the temperature distribution . To apply the lateral linear extension in course -wise direction to the fabrics, two movable jaws were designed and assembled . Using this device, fabrics were exposed to linear non - uniform extension levels in the range of 5% to 30%. A hot plate apparatus was used in order to investigate the temperature distribution. The temperature of the hot plate was set to 35 ?C and the fabric was placed on the hot plate. After reaching the steady state condition, the thermal image of cold side was then captured by an infrared thermal camera. Furthermore , simulating the temperature distribution in course -wise extended weft -knitted fabrics by considering different extension levels was another aim of this study. For the theoretical evaluation, meso and macro -scales were considered. In meso -scale, the fabrics’ corresponding geometrical unit cells were established in a finit e element software environment (Abaqus) using Python programming. In macro- scale, fabric was considered as a shell structure. The low absolute errors of thermal conductivity (7.31%) and thermal resistance (7.67%) show that t here was an acceptable agreement between the experimental and numerical modeling results. It has been concluded that surface temperature distribution in weft -knitted fabrics, induced by applying non -uniform lateral extension, could be properly simulated by computational modeling. Also, diff erent extension levels of the weft -knitted fabrics significantly affected the temperature distribution in these structures. In addition, it could be stated that the highest thermal conductivity is related to the plain single jersey knitted structure in com parison to the rib and interlock knitted structures.