Numerous scaling laws have been developed based on laboratory experiments, field experiments (e.g., TNT explosions), and computer models. There might be a more recent review, but the one by Johnson et al. (2016) is usually my go-to for the impactor-crater scaling laws (their equations 4 and 5 are slightly different, but close enough for most work).
To use them, you have to know the density of the target and body, diameter of the impactor, velocity of the impactor, surface gravity of the target, the simple-to-complex transition, and angle of impact. The simple-to-complex transition diameter is different for different bodies but is the approximate diameter below-which you get simple, bowl-shaped craters, and above-which you get complex craters with flat floors, central peaks, and/or wall terraces.
In the inner solar system, where rocky bodies are hit mostly by rocky asteroids, a very, very rough rule-of-thumb is you can tend to get craters very roughly 20 times the size of the impactor (e.g., Meteor or Barringer Crater in Arizona, roughly 1.2 km across, was probably formed by an iron-nickel meteorite 50 m in diameter). As I said in the previous paragraph, this depends on a lot of different parameters, so changing any of them will get you a different crater size without changing the actual size of the impactor. But, out where Pluto is, with more icy bodies striking each other at much slower speeds, the ratio is closer to a crater forms around twice the size of the impactor.
These scaling laws are still active areas of research, but at this point, the numbers are unlikely to change significantly with more data.
