What are the variables that enter into the formula for the Schwarschild Radius of a black hole?

         2 G M
R =   ----------
           2
          c

G = Constant of gravity = 6.6 x 10^-8 ( cgs units) ;

M is the mass in grams of the object forming the black hole

c = speed of light = 3 x 10^10 cm/sec.

After plugging in the constants you get

R = 2.96 m

where m is the mass in solar units. A supermassive black hole with m = 2 billion suns would have a radius of 6 billion kilometers or approximately the radius of Pluto's orbit.

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