The most popular method of reducing joint resistance R j is by increasing overlap length l. A numerical model capable of simulating the relationship between joint resistance and overlap length (the log(R j )-log(l) curve) could provide guidance for commercial high temperature superconducting joint manufacturing and may shed light on some more detailed behavior. In this study, a threedimensional model with an equivalent single homogeneous layer, characterized by resistance per unit area ρ s (Ω m 2 ), is developed and tested against experimental data. With this model, detailed measurement of parameters such as the thickness and resistivity of each layer and the interfacial resistance are not necessary. The log(R j )-log(l) relationship, especially for longer joints (l>20 cm), can be predicted by employing only ρ s , which can be experimentally and accurately obtained from shorter joints (l20 cm). The log(R j )-log(l) curve exhibits a nonlinear relationship when the overlap length exceeds a certain threshold value, in contrast to the commonly considered R j =ρ s /wl relationship (where w is the width of the joining area). This result is validated by accurately measuring the resistance of soldered joints with overlap lengths of 5-90 cm. The sensitivity of simulation results by different n values, I j /I c , and meshing precision levels are also presented.