What is the world's smallest mammal by body length?

The world's smallest mammal by body length is the bumblebee bat, also called Kitti's hog-nosed bat. It measures only about 29 to 33 millimeters from head to body, roughly the length of a large fingernail, and weighs around 2 grams.

This tiny bat, Craseonycteris thonglongyai, has a distinctive pig-like snout, relatively large ears, and a reddish-brown or gray coat. It lives in limestone caves in western Thailand and southeastern Myanmar. The species leaves its roost briefly at dusk and dawn to hunt small insects in nearby forest and agricultural areas.

The title “smallest mammal” depends on the measurement used. The bumblebee bat is generally recognized as the smallest by body length and skull size, while the Etruscan shrew is often cited as the smallest by body mass. That distinction explains why both animals appear in trivia lists. Despite its tiny size, the bumblebee bat is a fully powered-flying mammal and uses echolocation to navigate and find prey.