The Wikipedia page for planetary nomenclature states that small craters don't follow the same rule as large craters as far . What is the cutoff between small and large craters (as far as naming is concerned), if there is one at all? Is there a crater diameter under which craters are named for Earth towns and over which craters are named for scientists and writers?
Approximately 50km, according to the IAU documentation on namimg planetary features
In practice, there is some overlap, with some smaller craters having names of scientists (often these are craters that were named in 1973) and some larger ones having place names, such as Bamburg