The authors differ on the origin of this surname. E. Rossoni proposes that Carra, together with Carrà and Carrai, would derive from the trade of carraio (cartwright or maker of carts), although he notes that it could also refer to the trade of carrier or merchant. Rossoni places the main area of Carra between the Mantua and Parma areas, with presences also in the Lecce area and in that of Palermo. Carrà would present two independent clusters: one in the Pavia and Piacenza areas, and another in the Vibo Valentia area. Carrai, on the other hand, is typically Tuscan, with concentration in the Florence area.

For the origin of the surname in Sicily and Calabria, Rossoni provides a different explanation: in the dialect of Greek origin of the Bova area, in Calabria, the term karro means "downy oak", which would have motivated the surname as a reference to a wooded spot. Along the same lines, V. Blunda maintains that the surname comes from the Greek carro, "oak grove, wood of Turkey oaks", alluding to the Quercus cerris, a tree species of central and southern Europe, and relates it to the surnames Carrìa and Carro.

Rossoni also adds that in Sardinian, carra or cuàrra is a unit of measure for cereals and lands, and that the surname is documented in Sardinia among the signatories of the Peace of Eleonora of 1388. P. Durante, for his part, points to a Greek origin linked to the maker of carts, with possible relation to the Latin currus, although without developing the proposal.