Planck length

The Planck length () is an extremely small unit of length. It is calculated from three physical constants: the speed of light, the Planck constant, and the gravitational constant. The length was established as a way to simplify many of the more fundamental equations — if you write down equations in Planck units, you can do away with many physical constants and not have to worry about dimensions. The Planck length does not have any precise physical significance, and it is a common misconception that it is the inherent pixel size of the universe.
It is about 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 approximately the size of the smallest black holes.