Newton’s law of universal gravitation

For two bodies having masses m and M with a distance r between their centers of mass, the equation for Newton’s universal law of gravitation is

F = G mM /r²,

where F is the magnitude of the gravitational force and G is a proportionality factor called the universal gravitational constant.
G is a universal gravitational constant—that is, it is thought to be the same everywhere in the universe.
It has been measured experimentally to be
G = 6.674×10⁻¹¹N⋅m²  / kg²
in SI units.

Note that the units of G are such that a force in newtons is obtained from F = G mM /r², when considering masses in kilograms and distance in meters.