D = Crater Diameter
Cf = Crater Collapse Factor ( this is equal to 1.3 for craters >4km on Earth)
ge = Gravitational Acceleration at the surface of Earth
g = Acceleration at the surface of the body on which the crater is formed
W = Kinetic Energy of the impacting body (in kilotons TNT equivalent)
pa = Density of the impactor (ranging from 1.8g/cm3 for a comet to 7.3g/cm3 for an iron meteorite).
pt = Density of the target rock
Note: Typical impact velocities for asteroids are around 20km/s and approximately 60km/s for comets.