The authors differ on the etymology. E. Rossoni proposes that the surname would derive from a nickname of Greek origin formed by the union of kalos, "good", and fatis, "fame", which would indicate that the founder of the lineage was a person of good reputation in his community. He does not rule out, however, that in some cases it may derive from the trade of caulker.

V. Blunda leans directly towards this second hypothesis: according to him, the surname comes from the Greek calafàtes, which designates the craftsman who seals the joints of boats with oakum and pitch, and would have functioned as a trade nickname applied to the ancestor dedicated to nautical work.

As for the geographical distribution, Rossoni documents the form Calafato in the Palermo area, the Trapani area —specifically Mazara del Vallo—, the Agrigento area —Palma di Montechiaro, Ravanusa and Licata—, the Caltanissetta area —Riesi— and in Naples. He also records the variant Calafati in the Vibo Valentia area, in particular in Cessaniti, within Calabria.