The gravitational constant depends upon

The gravitational force between any two bodies that have some mass is given as:

${\text{F}}_{ }=\text{G}.\frac{{\text{m}}_{\text{1}}{\text{m}}_{\text{2}}}{{\text{r}}_{ }^2}$
Where m₁ and m₂ are the masses of the two bodies, r is the distance between them and G is the universal gravitation constant.
$G= 6.67 X {10}^{-11} N{m}^2/k{g}^2$

The value of G is constant for any two bodies involved and is independent of the medium in which the bodies lie.

The universal gravitational constant is independent of all the factors except the system of units.