Forearm length: 54-70 mm.
The upper parts of N. albiventris are grayish brown to yellowish in color or bright red. Typically color is sexually dimorphic, with males being bright red and females dull brown and drab. Individuals have a paler middorsal line and paler underparts. The nose of these bats is very pointy, but has no nose leaf or other projections. The tail extends about half of the length of the well-developed uropatagium. The relatively short hind limbs are almost completely free from the wing membrane. The wings of N. albiventris are long and narrow in comparison to other families within Microchiroptera. Noctilio albiventris can be distinguished from its close relative N. leporinus by its smaller size, smaller hind limbs and smaller claws on the hind feet (Nowak 1994).
Range mass: 18 to 44 g.
Range length: 57 to 85 mm.
Other Physical Features: endothermic ; bilateral symmetry