The present disclosure relates to a method and apparatus for accurate RC extraction. A pattern database is configured to store layout patterns and their associated 3D extraction parameters. A pattern-matching tool is configured to partition a design into a plurality of patterns, and to search the pattern database for a respective pattern and associated 3D extraction parameters. If the respective pattern is already stored in the pattern database, then the associated 3D extraction parameters stored in the database are assigned to the respective pattern without the need to extract the respective pattern. If the respective pattern is not stored in the pattern database, then the extraction tool extracts the pattern and stores its associated 3D extraction parameters in the pattern database for future use. In this manner a respective pattern is extracted only once for a given design or plurality of designs. Moreover, the extraction result may be applied multiple times for a given design simultaneously, speeding up computation time. The extraction result may also be applied to a plurality of designs simultaneously.