its a bit more complicated than that!
a is acceleration due to gravity
velocity is measured in 'x' units per second, x being feet or meters
radius is the simple radius of the turn, for this calculation, in feet or meters
from the equation above, divide 'a' by 32 ft/sec/sec to get the g force.
this is an overly simplistic value, but generally is good for your purposes.
If you wanted to, you could get really technical, and figure the bank angle, degree of curvature (ie in a 2nm radius turn with a delta of 30 degrees) coupled with the weight of the pilot times the COS of the bank angle..in the full banked turn. This makes sense when you look at making a turn, with only for a few degrees of change vs a 90 degree or more.
The equation above can also be used in the vertical direction, but since that is a parabola, you would have to simplify the apex into the simple radius for the max. You will see negative G forces, which means you are reducing the weight associated with the force due to gravity.