Formula racing, also known as open-wheel racing in North America, is any of several forms of open-wheeled single-seater motorsport. A "formula", first devised by FIA for its post–World War II single-seater races, is a set of regulations for a given type of car. The best known are Formula One, Formula E, Formula Two, Formula Three, regional Formula Three and Formula Four. Common usage of "formula racing" encompasses other single-seater series, including the IndyCar Series and the Super Formula Championship.

Lower categories such as Formula Three and Formula Two are described as junior formulae, lower formulae, or feeder formulae, referring to their position below top-level series like Formula One on their respective career ladders of single-seater motor racing. There are two primary forms of racing formula: open formula, which allows a choice of chassis or engines; and control or "spec" formula, which specifies a single supplier for chassis and engines. Formula Three is an example of an open formula, while Formula BMW is a control formula. Exceptions include Formula Ford, which has an open chassis formula but a single-brand engine formula.

While Formula One is the most expensive form of motorsport in the world, not all formula series are high-cost professional events. Some formulas are intended for juniors and amateurs; Formula 1000 and Formula Vee are among the least expensive forms of circuit racing.

Most contemporary formula categories allow the use of racing slicks, and extensive use of wings and ground effects to increase cornering speeds. However, there are popular amateur categories such as Formula Ford and Formula Vee which do not, and consequently have much slower cornering speeds and in which “drafting” plays a much more important role. Occasionally the term “wings and slicks racing” is used to distinguish the faster categories.

While reviving Grand Prix racing after World War II, the Fédération Internationale de l'Automobile's Commission Sportive Internationale defined the standardised regulations of Formula One (F1) in 1946. The first race to be run to the early Formula One regulations was a non-championship Grand Prix in Turin in September 1946. The first officially recognised Formula One season was held in 1947 and the World Championship for Drivers was inaugurated in 1950.

Formula E is the highest class of competition for single-seat, electrically powered racing cars, which held its inaugural season in 2014–15. Conceived in 2012, the championship was intended by the FIA to serve as an R&D platform for the electric vehicle and promote interest in EVs and sustainability. The series races predominately on temporary circuits in cities such as New York, Hong Kong, Zürich, Berlin, Rome, and Paris in events known as "ePrix". In order to cap costs but maintain technological development, the series uses a spec chassis and battery that must be used by all entrants, with competing teams permitted to design and build their own motors, inverter and rear suspension. The series has gained traction in recent years.

The FIA Formula 2 Championship was introduced in 2017 by Bernie Ecclestone and Flavio Briatore following the rebranding of the long-term F1 feeder series – GP2 Series. Designed to make racing affordable and to make it the perfect training ground for life in F1, F2 has made it mandatory for all of the teams to use the same chassis, engine, and tyre supplier.

In 2019, the GP3 Series was replaced by international Formula 3, just in the same way that GP2 was rebranded as Formula 2 in 2017. The series' first drivers' champion was Robert Shwartzman driving for Prema Racing, who also won the teams' championship that year. Before 2024, the FIA Formula 3 World Cup took place at the end of the season at the Macau Grand Prix. However, due to various reasons, it has been discontinued. Formula Regional category cars have raced in place of Formula 3 cars at the Macau Grand Prix since then.