It is the smallest species of chipmunk, measuring about 15.7–25 cm (6.2–9.8 in) in total length with a weight of 25–66 g (0.88–2.33 oz).

[4] In some areas, where range overlap with the yellow-pine chipmunk occurs, it may be difficult or impossible to distinguish the two species in the field; laboratory examination of skeletal structures may be required.

[citation needed] Least chipmunks spend the winter in burrows and also scatter-hoard food in numerous concealed pits beneath logs and similar cover.

[4] During the summer they may construct temporary nests in trees from leaves and grass,[12] or appropriate hollows made by woodpeckers.

Instead, they survive the winter by entering torpor for long stretches of time, waking to eat food cached in the burrow.

[4] Females enter estrus within a week of emerging from their burrow in the spring, and mating typically takes place between March and May.