The Association of Zoos and Aquariums requires that a single adult elephant is provided with 1,800 square feet of outdoor space and 400 square feet of indoor space. There is no upper limit on space; zoos are encouraged to offer as much space as possible.
Elephants in the wild are known to roam through areas as large as 640,000 acres. Zoos are not capable of providing elephants with this much space. Most elephant enclosures are less than 1 acre, though some zoos do offer larger enclosures of up to 5 acres that give the elephants more space to walk and explore.