The little brown myotis is a medium sized bat. Fur on its back is brown, ranging from yellowish to dark brown-black, and often glossy. Fur on its underside is lighter and goes from light brown to tan. The tragus (fleshy projection that covers the entrance of the ear) is short and blunt. Females tend to be slightly larger than males.
Wingspan: 22 to 27 cm (9 to 11 in), Weight: 7-14 g (0.3 to 0.5 oz).