In this paper, we describe the expression curvature of discrete waypoints and its application to autonomous driving. In the applications of autonomous driving, in control aspect, it is important to know the exact information of curvature of the waypoints to be followed. Previous approaches have adopted polynomial fitting to calculate the curvature. While this polynomial-fitting approach is easy to use, fitting is time-variant in its nature. This leads to inconsistent curvature estimation, which introduces undesirable control. Through the method presented in the paper, gives time-invariant consistent curvature estimation and is verified in a real-world autonomous platform, the USRG Tram.