The authors agree that this surname has a presence in the centre-north of Italy, with a greater frequency in Tuscany, and extends towards the south as far as Campania and Apulia. The documented variants include Tozzini, Tozzo and Tozzato.

E. Rossoni proposes that the surname could derive from the loss of the initial syllable of medieval names such as Lutozzo, or else from hypocoristics of names such as Alberto, Roberto or Dagoberto that underwent the same process of reduction. Rossoni documents Tozzi in a wide strip from Liguria and Emilia-Romagna to Campania and Apulia; Tozzini in the Pisa area, with a presence in the Florence, Livorno and Grosseto areas; and Tozzo in the Vicenza area, with smaller nuclei in the Ancona and Rome areas and in the area between Catanzaro and Vibo Valentia.

V. Blunda proposes, for the Sicilian variant, a Germanic origin from the personal name Tozi, a hypocoristic form linked to a Lombard onomastic base of debated etymology, possibly connected to reduced forms of compound anthroponyms. According to Blunda, the consonantal doubling with sibilant -zz- is characteristic of medieval Italian phonetics to indicate affective forms of the original name.

E. De Felice notes that the surname was formed from various etymons and processes, without specifying a single etymology, and documents the variant Tozzato as typical of Veneto.