The tensile strength of clay is a major mechanical parameter and the main controlling parameter of tensile crack development which is generally encountered in geostructures. In this experimental study, 8-shaped direct tensile test and split tensile test were used to measure the tensile strength of compacted clay soil. Unconfined compression tests on the same clay samples were also carried out. Tensile strength and unconfined compression test results were compared. Laboratory tests were performed on Ankara clay and Kaolin clay with the addition of various proportions of synthetic polypropylene fiber, pulverized rubber, metal swarf, and bentonite. The data between the results of 8-shaped direct tensile tests, split tensile tests, and unconfined compression tests were correlated. This usage of different stabilizing agents enabled the authors to observe the reliability of the tensile strength measurement methods when soils' mechanical properties were significantly changed and to develop universal equations which also can be applied to stabilized soils. The ratio of 8-shaped tensile strength to split tensile strength and to unconfined compressive strength was calculated to be 1.9 and 0.4, respectively. Also, the ratio of split tensile strength to unconfined compressive strength was calculated to be 0.2. Three equations were developed according to the Ankara clay and Kaolin clay mixtures' tensile strengths, index properties, and compaction characteristics and proposed to estimate the tensile strength of fine-grained soils from their index properties.