This study proposes a method of calculation to estimate partial discharge inception voltages in ultradilute SF 6 + N 2 gas mixtures. The method is based on the condition necessary for the initial streamer to propagate in a gap where the electric field distribution is highly non-uniform. The proposed method utilizes the finite element method (FEM) in determining the electric fields in ultradilute SF 6 + N 2 gas mixtures. The analysis is applied for rod-plane gaps. Since the average errors are less than 5%, it is recommended to use the proposed simulation model to predict partial discharge inception voltages in ultradilute SF 6 + N 2 gas mixtures.