AbstractCores were drilled from the panels made of different concrete mixtures. The compressive strength and splitting strength of core and cube specimens were tested at the ages of 7, 28, 60, 90, and 180 days. The effect of the diameter on concrete core splitting strength was examined. The strength correction factors were determined to convert the splitting strength of the core with diameter of 75 mm to that of the core with diameter of 100 mm. The regression analysis was carried out using experimental data to evaluate the core splitting strength as a function of the compressive strength of the concrete core. Then, the reliability of the proposed equation based on experimental data for compressive strength ranging from 20 to 80 MPa was assessed with the integral absolute error (IAE). Other existing relations between splitting strength and compressive strength of the cylinder were also evaluated with IAE, and most of the existing relations are not suitable for splitting strength of cores. The accurate power function relation formula is obtained with the test data. Only compressive test can be carried out by using drilling core samples in existing buildings, and the compressive strength and tensile strength of concrete can be obtained simultaneously, thus the numbers of splitting tests can be reduced and the mechanical property of existing buildings can be evaluated.