The western pipistrelle bat is the smallest known species of bat in the United States, and it weighs less than a penny, while the greater mastiff bat is the largest known species in the U.S., and it weighs around 2 ounces. There are multiple different bat species that vary in typical weight.
Although different bat species weigh various amounts, they are all generally lightweight. Their low weights allow them to more easily fly. Bats have a considerable wingspan considering their low weight. The western pipistrelle bat has a wingspan of about 8 inches, while the greater mastiff bat has a wingspan of 21 to 23 inches.
Their ears are one of their most notable features. The ears on the Allen's big-eared bat make up as much as 2/3 its total body size. Their large-sized ears allow them to use their sonar communication tactics better, since most bats have poor eyesight.
Despite their small size, bats are quite durable and live for a long time. Most bats that make it to adulthood have the potential to live into their teens, and some can even live for 20 or more years. However, most bats do not live that long due to the considerable mortality rate among young bats.