A passenger side airbag model in CAL3D for occupant dynamics analysis is presented. Two new features, an advanced inflator model and a multi contact ellipsoid method for describing bag shapes, are used in this model. The advanced inflator model can be used to estimate both gas temperature in the inflator, which is crucial in simulating the large gas leakage from a passenger airbag, and mass flow rate from the inflator. The multi-contact-ellipsoid method allows more than one contact ellipsoid to be attached to an airbag. These ellipsoids can then approximate a non-ellipsoidal bag shape such that the local contacts between the bag and the occupant/vehicle system may be accurately simulated. The existing computation scheme of the program for evaluating the airbag volume and gas dynamics is preserved. Illustative examples are presented. It shows that the method is easy to use, efficient in computation, and accurate enough to be used as a design tool for passenger side airbag systems.