In the present work, an equation has been developed to calculate the side length of the equilateral triangular patch for given resonant frequency. With the previously existing equation poor accuracy has been achieved for the performance parameters of the triangular microstrip patch antenna. Modified formula enhances the accuracy of the performance parameters of the triangular microstrip patch antenna. Proposed formulae provide a nonlinear relationship between the resonating frequency and the dimensions of the equilateral triangular patch antenna i.e. the required performance parameters and the design parameters used in the simulation and fabrication process. With the help of calculated dimension, performance of triangular patch antenna has been analyzed for particular resonating frequency. Simulated results of proposed equation have been compared with the existing equation, and better accuracy in the results has been achieved with the improved formula. Proposed equation has been verified by simulating and fabricating various antennas, and measured results are found satisfactory.