It is equal to 1.616 255 (18) × 10 m ‍ (the two digits enclosed by parentheses are the estimated standard error associated with the reported numerical value) or about 10 times the diameter of a proton. It can be motivated in various ways, such as considering a particle whose reduced Compton wavelength is comparable to its Schwarzschild radius, though whether those concepts are in fact simultaneously applicable is open to debate. (The same heuristic argument simultaneously motivates the Planck mass.)