Planck length

very small-scale unit of length

The Planck length (P) is a very small unit of length, and the smallest unit of length that exists because the laws of the universe will literally stop working at smaller scales. It is calculated from three physical constants: the speed of light, the Planck constant, and the gravitational constant.

It is about 1.616255×10−35 m or about 10−20 times the size of a proton. It is one of the Planck units, defined by Max Planck. It is an important length for quantum gravity because it may be the size of the smallest black holes.[1]

Related pagesEdit


  1. Baez, John. "The Planck Length".