In this paper we present a new way to calculate channel length shortening in saturation for standard bulk MOSFETs by solving 2D Poisson's equation. Compared to most existing models, we use in our model only physically meaningful and geometry-independent fitting parameters, which gives our model a good scalability. 2D Poisson is solved in analytical closed form by applying the conformal mapping technique. This gives the model the advantage additionally to its application in circuit simulations to be useful in calculating device scaling behavior. Our model describes the output conductance of MOSFETs down to 50 nm effective channel length very well. (C) 2008 Elsevier Ltd. All rights reserved.