The 2021 FIA World Endurance Championship was the ninth season of the FIA World Endurance Championship, an auto racing series organised by the Fédération Internationale de l'Automobile (FIA) and the Automobile Club de l'Ouest (ACO). The series is open to prototype and grand tourer-style racing cars divided into four categories. World Championship titles were awarded to the leading manufacturers and drivers in both the prototype and grand tourer divisions. The 2021 championship was due to see a significant overhaul of the technical regulations in the top class of competition. The LMP1 Prototypes used in the top class for the first eight years of the championship had been phased out and replaced by a new prototype specification known as Le Mans Hypercars (LMH). However, non-hybrid LMP1 cars were permitted to be "grandfathered" into the season. The 2021 championship also marked the return to an annual calendar for the World Endurance Championship, switching back to a summer calendar after the late running of the previous season due to the COVID-19 pandemic. Calendar A calendar was revealed in December 2019 at the 8 Hours of Bahrain. Due to the COVID-19 pandemic, the previous season was extended into November 2020. However, the 2021 season will return to an annual calendar entirely instead of a winter calendar. A calendar for the 2021 season was announced during the 2020 24 Hours of Le Mans event. The calendar featured six rounds as opposed to eight and saw the removal of the 6 Hours of Silverstone, 6 Hours of Shanghai and Lone Star Le Mans when compared with the 2019–20 calendar as well as the addition of the 6 Hours of Monza. The decision to run a six-round series was made to save on costs due to the financial impact of the pandemic. The 1000 Miles of Sebring was initially scheduled for 19 March 2021 as the first round of the season, but was cancelled in response to the COVID-19 pandemic and replaced by a race of the same length at Portimão on 4 April 2021. That same race would also be itself later postponed to 13 June, making Spa the site of the preseason Prologue and the first race of the season. The 24 Hours of Le Mans was originally scheduled to be run on the 12 and 13 June but was later postponed until 21–22 August for an increased chance of running the race with spectators.