What is the world's smallest mammal?

By size, the world's smallest mammal is the bumblebee bat (Craseonycteris thonglongyai), a species native to Thailand. This species of bat is roughly the size of a bumblebee, with a body and head size of around 1 inch and a typical weight of about 0.7 ounces.

Although the bumblebee bat is the world's smallest mammal by size, a close runner up for smallest mammal by weight is the Etruscan shrew (Suncus etruscus), whose typical weight is comparable to that of the bumblebee bat. The Etruscan shrew, however, is slightly larger in size than the bumblebee bat, measuring around 1.5 inches.