伯格曼法则（英语：Bergmann's rule）是动物学中广泛接受的的一种规律，指同一种类恒温动物的体形会随着生活地区纬度或海拔的增高而变大。比如生活于北极地区的北极熊就比其他地区的熊类体形更庞大。同样地，北极狼也比温带地区的狼类个子更大。该定律是以19世纪德国生物学家卡尔·克里斯琴·伯格曼（Carl Christian Bergmann）的名字命名的。

也有研究发现，有些昆虫类群个体大小随纬度升高而增加，符合伯格曼法则。

反伯格曼法则则认为随着纬度升高, 生长季缩短, 动物的发育时间相应减少, 因而生物体型会变短变小。

Bergmann's rule is an ecogeographic principle that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been recast in terms of populations within a species. It is also often cast in terms of latitude.