The consulted works concur in tracing the surname Manfrin and its related forms to medieval personal names of Germanic origin. E. Rossoni establishes the geographic distribution of the main variants: Manfrin is proper to the Veneto region; Manfrini shows three distinct areas of presence — one in the south of Trentino-Alto Adige, another in the area of Ferrara, and another in the area of Ancona; Manfrino, for its part, is attested in a small area around Turin — specifically in Druento and Turin — and in the area of Savona. Rossoni traces these forms to the medieval Latin name Manfrinus, documented in a deed from Milan dated 1494, and notes that in infrequent cases the forms may derive from dialect modifications of the medieval Germanic name Manfredi.

F. De Laurentiis adds that Manfrin is specifically a Venetian derivative of Manfredini, suggesting a more precise regional chain of derivation that complements Rossoni's broader Germanic hypothesis. The underlying Germanic personal name is analyzed in the sources as well: it is recorded as a compound of magin, meaning "power," and frithu, meaning "peace" or "friendship," transmitted into Italian through the Lombard form Manfredo.