The authors agree that this surname derives from the place name Trento. E. De Felice notes that it was formed from that place name and locates it in the north-east of Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige, as well as in Lombardy and Emilia-Romagna.

E. Rossoni offers a more detailed analysis, distinguishing several forms of the surname. Trenti is concentrated in the Trentino-Alto Adige region and in the Modena area. Trentin appears in the Trento area and extends across the Vicenza, Treviso and Padua areas. Trentini runs through a strip that goes from Trentino-Alto Adige, passing through the Verona and Mantua areas, to the Modena, Bologna and Ferrara areas. The form Trento, used as a surname, is recorded in the Vicenza, Padua and Treviso areas.