The application of the mapping method in finite element modeling is extended to quantitatively compare mixing in different twin-screw extruder layouts. The mapping method provides volumetric quantities, which are crucial for the analysis and optimization of mixing based on the tracking of particles in the velocity field. A new approach to the mapping method is developed to analyze mixing in complex, dynamic open geometries. Several screw configurations and different types of conveying screws are compared, changing the pitch and gap widths. The volume-weighted intensity of segregation is used as a mixing measure.