A vehicle seat weight classification system includes a recalibration strategy to ensure sensor accuracy over time. A controller preferably is programmed to periodically sample outputs of the sensors when a seat is unoccupied. Average sensor output information is compared to a currently stored calibration value. If the newly determined average value meets selected criteria, then the sensor is recalibrated using the new information. The system and method of this invention compensates for changes in sensor performance over time caused by changes in system characteristics, such as material offset drift.