How large are the cooking grates?
In the 18-1/2″ WSM, the top grate is 17-1/2″ in diameter and is the same one used in all Weber 18-1/2″ charcoal grills. The bottom grate is 17″ in diameter. The combined surface area of the two cooking grates is about 468 square inches. In the 22-1/2″ WSM, the top grate is 21-1/2″ in diameter and is the same one used in all Weber 22-1/2″ charcoal grills. The bottom grate is 20-3/4″ in diameter. The combined surface area of the two cooking grates is about 701 square inches.