The grades issued by the FIAFédération Internationale de l'Automobile is the association responsible for the interests of motoring organisations and motor car users across the... There's more... range from 1 to 6 depending on the suitability of the circuitA circuit is a racetrack for car racing. There's more... for different types and groups of cars, with 1 being the highest grade and the only circuit that can host Formula OneFormula One is the pinnacle of open wheel, single seater car racing and arguably the highest level of any motorsport... There's more... races.
Grade 1 circuits are for cars that have a weight/power ratio of less than 1 kg/hp (Grade D & E cars). The specification of the tracks is very specific with total length, length of straights, and width all defined, among other criteria. Safety features are of the highest standard, for the protection of the drivers and spectators, as well as a fully equipped medical centre and qualified staff.
As of 2022, there are 38 Grade One circuits with a total of 46 possible layouts.
Autosport has a great article that delves into the detail. Read it on sutosport.com – here