The Western Barbastelle is medium sized and has long black pelage with white or yellow tips. The underside of the body is somewhat paler. Fur covers parts of the uropatagium and the wings, and the tail is nearly as long as the body. It is distinguishable among other European bats by its short wide ears that face forward and connect across the brow. The female is significantly larger than the male; combined ranges of measurement are as follows: head and body, 45-60 mm; wingspan, 245-300; tail length, 36-52. (Nowak 1999, Rydell and Bogdanowicz 1997)
Range mass: 6 to 10 g.