F4

F4, F.IV, F04, F 4, F.4 or F-4 may refer to:

Aircraft

 * Flanders F.4, a 1910s British experimental military two-seat monoplane aircraft
 * Martinsyde F.4 Buzzard, a British World War I fighter version of the Martinsyde Buzzard biplane
 * Fokker F.IV, a 1921 Dutch airliner
 * Caproni Vizzola F.4, an Italian prototype fighter of 1939
 * Lockheed F-4 Lightning, a reconnaissance variant of the Lockheed P-38 Lightning World War 2 fighter
 * Fleetwings Sea Bird, a variant of which was the F-4
 * A number of aircraft that first entered service with the U.S. Navy:
 * Curtiss F4C, a 1920s version of the Naval Aircraft Factory TS biplane fighter
 * Boeing F4B, a 1930s version of the Boeing P-12 biplane fighter
 * Grumman F4F Wildcat, a carrier-based fighter aircraft in World War 2
 * Vought F4U Corsair, a World War 2 fighter
 * Douglas F4D Skyray, a carrier-based fighter/interceptor, first flight 1951
 * McDonnell Douglas F-4 Phantom II, a supersonic fighter-bomber, first flight 1958

Art, entertainment, and music

 * F4, or Flower 4, the four handsome boys appearing in Japanese manga Boys Over Flowers
 * F4 (band), Taiwanese boy band
 * F4 Thailand, a Thai television series
 * F4, Middle F (musical note)
 * Fantastic Four, fictional superhero team

Computing and technology

 * Faugère's F4 algorithm in computer algebra
 * F4, a function key on a computer keyboard
 * f4transkript, a transcription software
 * Samsung Galaxy F04, an Android-based smartphone manufactured by Samsung Electronics

Mathematics

 * F4 (mathematics), the name of a Lie group and also its Lie algebra f4
 * F4, Fermat number
 * F4, Fermat number

Sports and games

 * F4 (classification), a wheelchair sport classification
 * Formula 4, a class of car racing
 * f4, designates a square in Algebraic notation (chess)
 * 1. f4, or Bird's opening, an opening move in chess

Transportation and vehicles

 * F4 (Istanbul Metro), a funicular railway in Istanbul Turkey
 * F4 Cross Harbour, or Cross Harbour ferry services (2017–2020), Sydney, Australia
 * F4 Pyrmont Bay, or Pyrmont Bay ferry services, Sydney, Australia
 * Albarka Air (IATA code), a Nigerian airline
 * Front-engine, four-wheel-drive layout, in automotive design
 * MV Agusta F4 series, a series of motorcycles
 * Saginaw Airport (FAA identifier F04), a defunct public airport in Fort Worth, Texas, U.S.
 * USS F-4, a U.S. Navy submarine that sank near Honolulu harbor in 1915
 * LNER Class F4, a class of British steam locomotives

Other uses

 * F4, a paper size
 * F 4 Frösön, a former Swedish Air Force wing
 * f/4, an f-number of an optical system such as a camera lens
 * F-4 Object, or Rákosi bunker, a formerly secret nuclear shelter in Budapest, Hungary
 * Form F-4, an American form used to register securities
 * Nikon F4, a camera
 * F4, a tornado intensity rating on the Fujita scale
 * F4, an electrode site according to the 10–20 system (EEG)