E. Rossoni notes that this surname derives from the late Latin word caligarius, which designated the shoemaker, that is, one who made or traded in footwear, from the Latin caliga. As an illustrative fact, the Roman emperor Caligula himself took his name from this term: as Tacitus relates in the first book of his Annals, as a child he wore this type of military footwear to win the affection of the soldiers.

Rossoni identifies the form Callegaro as typical of Veneto, with a presence in the Rovigo, Padua, Venice and Treviso areas, and also in the Udine area. The surname has independent origins in different regions of Italy and covers kindred forms: Calegari in the Bergamo and Milan area; Calegaro in the Verona area; Caligari in the Sondrio area and in Emilia-Romagna; Caligaris in Piedmont, Liguria and western Lombardy; Callegari in northern Italy; Calligari in the Milan, Pavia and Novara area; and Calligaris in Friuli, with a presence in the Udine, Gorizia and Trieste areas.

F. De Laurentiis considers it a variant of Callegari, in agreement with what Rossoni notes.