F40, F.40, or F-40 may refer to:
Transportation Aircraft Farman F.40, a French pusher biplane reconnaissance aircraft Hirth F-40, a German aircraft engine F40, the NATO code for the JP-4 jet fuel
Automobiles Beijing F40, a Chinese subcompact pickup truck Ferrari F40, an Italian mid-engine sports car BMW 1 Series (F40), a German subcompact hatchback GM F40 transmission, a car gearbox
Trains EMD F40C, an American diesel-electric locomotive EMD F40PH, an American diesel locomotive
Watercraft Brazilian frigate Niterói (F-40), a Niteroi-class frigate of the Brazilian Navy HMS Jervis Bay (F40), a British armed merchant cruiser HMS Roberts (F40), a Roberts-class monitor of the Royal Navy HMS Sirius (F40), a Leander-class frigate of the Royal Navy INS Talwar (F40), the lead ship of the Talwar-class frigates of the Indian Navy
Other uses F40 (classification), a disability sport classification for athletes of short stature F40 (full name F40T12) is a common size fluorescent lamp, at 4 foot or 1.2m