List of motor racing circuits by FIA grade

Appendix O to the FIA International Sporting Code defines the inspection and licensing process for auto racing circuits intending to host races sanctioned by the Fédération Internationale de l'Automobile (FIA), motorsport's governing body. The grades issued by the FIA are 1, 2, 3, 4, 6 and FE, depending on the suitability of the circuit for different types and groups of cars, with 1 being the highest grade and the only circuits that can host Formula One races.

Source: Wikipedia — List of motor racing circuits by FIA grade (CC BY-SA 4.0)