The high conductivity of copper nanowires (CuNWs) with a diameter of less than 100 nm makes them promising candidates for various applications, including interconnects for nanoelectronics and flexible transparent conductive surfaces (TCS). One of the most important parameters is the resistivity of CuNWs, which is mainly determined by the size and structural imperfections such as surface and grain boundary scattering. Compact and exact models are used that accurately describe the resistivity for sub- 100 nm-wide CuNWs where the mean free path is comparable to the critical dimension of the nanowire. We analyze the resistivity as a function of diameter and various scattering parameters, such as specularity, reflectivity and mean grain size. We found that the grain boundary effect dominantly determines the resistivity while surface scattering acts as correction factor. We show that the expected resistivity is lower than 10×10−8Ω m, potentially indicating good applicability for high-conductivity TCSs even for structurally imperfect CuNWs.