Asteroid crater retention ages are poorly understood because no one knows which crater scaling laws are applicable to different bodies. By comparing results from a main belt collisional evolution model to asteroid cratering records, however, it is now possible to derive crater scaling laws. We find that fits to craters on Vesta, Lutetia, Mathilde, Ida, Eros, and Gaspra yield crater to projectile ratios near 10. If we apply this scaling law to the largest craters on smaller asteroids (e.g., Toutatis, Itokawa, Ryugu, and Bennu), we obtain crater retention ages that match the likely ages of their source families. Intriguingly, these ages are longer than their expected collisional lifetimes. This may suggest that (i) our model/data match is a fluke, (ii) most bodies escaping the main belt are ancient survivors, or (iii) the timescales of asteroid disruption events need to be reassessed.