Kleiber's law

Kleiber's law, named after Max Kleiber for his biology work in the early 1930s, is the observation that, for the vast majority of animals, an animal's metabolic rate scales to the 3⁄4 power of the animal's mass.^[2] More recently, Kleiber's law has also been shown to apply in plants,^[3] suggesting that Kleiber's observation is much more general. Symbolically: if B is the animal's metabolic rate, and M is the animal's mass, then Kleiber's law states that ${\displaystyle B\propto M^{3/4}}$. Thus, over the same time span, a cat having a mass 100 times that of a mouse will consume only about 32 times the energy the mouse uses.

The exact value of the exponent in Kleiber's law is unclear, in part because the law currently lacks a single theoretical explanation that is entirely satisfactory.