|The distance A to B is the wingspan of this Aer Lingus Airbus A320.|
The wingspan (or just span) of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about 60 metres (197 ft); and a Wandering Albatross (Diomedea exulans) caught in 1965 had a wingspan of 3.63 metres (11 ft 11 in), the official record for a living bird.
Wingspan of aircraft
The wingspan of an aircraft is always measured in a straight line, from wingtip to wingtip, independently of wing shape or sweep.
Implications for aircraft design and animal evolution
The lift from wings is proportional to their area, so the heavier the animal or aircraft the bigger that area must be. The area is the product of the span times the width (mean chord) of the wing, so either a long, narrow wing or a shorter, broader wing will support the same mass. For efficient steady flight the ratio of span to chord, the aspect ratio, should be as high as possible (the constraints are usually structural) because this lowers the lift-induced drag associated with the inevitable wingtip vortices. Long-ranging birds, like albatrosses, and most commercial aircraft maximize aspect ratio. Alternatively, animals and aircraft which depend on maneuverability (fighters, predators, the predated and those who live amongst trees and bushes, insect catchers, etc.) need to be able to roll fast to turn, and the high moment of inertia of long narrow wings produces lower roll rates. For them, short-span, broad wings are preferred.
The highest aspect ratio man-made wings are aircraft propellers, in their most extreme form as helicopter rotors.
Wingspan of flying animals
To measure the wingspan of a bird, a live or freshly dead specimen is placed flat on its back, the wings are grasped at the wrist joints, ankles and the distance is measured between the tips of the longest primary feathers on each wing.[clarification needed]
The wingspan of an insect refers to the wingspan of pinned specimens and may refer to the distance between the centre of the thorax to the apex of the wing doubled or to the width between the apices with the wings set with the trailing wing edge at right angles to the body.
Armspan in sports
In basketball and gridiron football, a fingertip to fingertip measurement is used to determine the player's armspan. This is called reach in boxing terminology. The wingspan of 16-year-old BeeJay Anya, a top basketball junior Class of 2013 prospect, was officially measured at 7 feet, 9 inches across, perhaps longer than any National Basketball Association draft prospect ever. 
- Aircraft: Hughes H-4 Hercules "Spruce Goose" – 319 ft 11 in (97.51 m)
- Aircraft (current) Antonov An-225 Mriya - 88.4 m (290 ft)
- Bat: Pteropus "Flying fox" or "fruit bat" – 2 m (6 ft 7 in)
- Bird: Wandering Albatross – 3.63 m (11 ft 11 in)
- Bird(extict): Argentavis – Estimated 7 m (23 ft 0 in)
- Reptile (extinct): Quetzalcoatlus pterosaur – 10–11 m
- Insect: White Witch moth – 28 cm (11.0 in)
- Insect (extinct): Meganeuropsis (relative of dragonflies) – estimated up to 71 cm (28.0 in)
- Aircraft (biplane): Starr Bumble Bee II – 1.68 m (5 ft 6 in)
- Aircraft (jet): Bede BD-5 – 4.27 m (14 ft 0 in)
- Aircraft (twin engine): Colomban Cri-cri – 4.9 m (16 ft 1 in)
- Bat: Bumblebee bat – 16 cm (6.3 in) 
- Bird: Bee Hummingbird – 6.5 cm (2.6 in)
- Insect: Tanzanian parasitic wasp – 0.2 mm (0.0079 in)
- Smith, Cameron (June 17, 2013). "High school basketball player’s stunning wingspan". Yahoo Sports!. Retrieved October 7, 2013.
- "Spruce Goose". Evergreen Aviation Museum. Retrieved June 23, 2007.
- "Bats". Sea World. Retrieved June 23, 2007.
- Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9.
- Chatterjee, Sankar; Templin, R. Jack; Campbell, Kenneth E.Jr. (2007). The aerodynamics of Argentavis, the world’s largest flying bird from the Miocene of Argentina 104 (30). pp. 12398–12403.
- Connor, Steve (September 10, 2005). "Flying dinosaur biggest airborne animal". New Zealand Herald. Retrieved June 23, 2007.
- "Largest Lepidopteran Wing Span". University of Florida Book of Insect Records. Retrieved June 23, 2007.
- Mitchell, F.L. and Lasswell, J. (2005): A dazzle of dragonflies Texas A&M University Press, page 47
- "STARR BUMBLE BEE". Pima Air & Space Museum.
- Adrienne Glick. "Mellisuga helenae bee hummingbird". Animal Diversity Web. Univertiy of Michigan. Retrieved 29 November 2013.
- "Smallest Insect Filmed in Flight". ScienceDaily. Retrieved 29 November 2013.