The authors agree that Bigaran and its variant Bigarani derive from a nickname based on the archaic Venetian term bigaran, which designated a bread of very high quality made in small rolls joined together. The surname would indicate that the first bearer was an excellent person —"good as bread"— or simply a good baker.

E. Rossoni places the main cluster of the surname in the area comprising the Treviso, Pordenone and Venice areas, with presence also in Trento and the Udine area, while the variant Bigarani appears as typical of the Massa area, in Tuscany.

F. Miranda broadens the geographical distribution and indicates that the surname is concentrated in northern Italy: Veneto —with notable clusters in the provinces of Treviso and Venice—, Friuli-Venezia Giulia —Pordenone, Udine and Gorizia areas—, Piedmont, Trentino-Alto Adige and Lombardy. Miranda also notes ramifications in Emilia-Romagna, Sardinia and Sicily.