In circuit design and device scaling investigations, there is still a demand for improved analytical models of MOSFETs with less fitting parameters and a good scalability. In this paper, PREDICTMOS-a predictive compact model for structure oriented simulation of MOS devices is presented which has been developed by use of strongly physics-based model equations. For threshold voltage, surface potential in weak inversion, and currents in strong inversion including the saturation regime, the equations have been derived using our recently published conformal mapping techniques for solving the two-dimensional Poisson equation, and a new way to solve the transistor current differential equation. They make use of real structural parameters without any need of physically meaningless fitting parameters. This results in a strong link between electrical parameters and the process and layout data of the device and an excellent scalability while keeping physical insight. PREDICTMOS has been implemented in the ELDO circuit simulator. Its results ill comparison with numerical device simulations and measurements show good agreement down to dimensions of 0.1 mu m.