The American pygmy shrew is the smallest mammal native to North America. Its is about 5 cm (2 in) long. It weighs about 2.0 to 4.5 g (0.07 to 0.16 oz). Its fur is reddish or grayish brown during the summer. It is white-gray during the winter. It molts about two times a year. It has a narrow head with a pointed nose, and whiskers. The eyes are small.