E. De Felice and E. Rossoni agree that the surname derives from a place name of northern Lombardy.

De Felice identifies it as a surname of upper Lombardy, frequent in Milan, formed from the ethnic of Ranco, a small centre of Lake Maggiore, in the province of Varese.

Rossoni, on the other hand, derives it from the place name Rancate, very diffused in the territories that belonged to the Duchy of Milan. He documents it with the form de Ranchatis and notes its presence in the Stemmario Trivulziano of the 15th century. He adds as an alternative hypothesis a derivation from the Pavese term rancà ("to pull up, to uproot"). He documents the surname in Milan from at least the beginning of the 15th century.