Threshold voltage (VTH) is a crucial parameter for the proper functioning of a transistor. In this study, we propose an alternative method, called the conductance-voltage method, to extract the threshold voltage. This method uses the change in drain current (IDS) with applied gate voltage (VGS) as the device transition from the weak accumulation to the strong accumulation mode of operation to estimate the threshold voltage. This method was then applied to pentacene-based and amorphous indium-gallium-zinc-oxide (a-IGZO)-based thin-film transistors (TFTs) in their linear region of operation using two-dimensional simulations. The results were promising, and this new method provides a valuable tool for optimizing the performance of Complementary Organic/Oxide TFTs for future applications.