In physics, the Planck length, denoted $\ell_P$, is a unit of length, equal to $1.616199(97)×10^{-35}$ metres. It is a base unit in the system of Planck units. The Planck length can be defined from three fundamental physical constants: the speed of light in a vacuum, Planck's constant, and the gravitational constant.
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0.00000000000000000000000000000000001616252
$\ell_P = \sqrt{\frac{ \hbar G}{c^3}} \approx 1.616199(97)) \times 10^{-35} m$, where $c$ is the speed of light in a vacuum, $\hbar$ is the reduced Planck's constant, and $G$ is the gravitational constant. The two digits enclosed by parentheses are the estimated standard error associated with the reported numerical value.