The authors agree that the surname derives from the Latin noun scala ("step, ascent, slope"), which in medieval language designated both stepped constructions and sloping geographic features and port landing points. The surname has independent origins in different regions of Italy, linked to the numerous place names containing that root: Scala (in the provinces of Messina, Salerno and Cosenza), Scalea (Calabria and Sicily), Scalera (Potenza) and Scaletta (Messina), among others.

E. De Felice notes that the dialect forms include the Sicilian and Calabrian scalea and the Sardinian (i)skala and its plural (i)skalas, with the meaning of "steep or terraced zone." He indicates a greater frequency of the base form in Liguria and in the Naples area, and places Scalas specifically in southern Sardinia.

E. Rossoni adds that a derivation from the medieval Germanic name Schal is also possible. He documents zones of concentration in the Verona area, the south of the Milan area, that of Lodi, that of Genoa, that of Bologna, that of Naples and in Sicily (Catania, Syracuse and Ragusa). For the variant Scali, he notes a nucleus in the Genoa area, a Tuscan one distributed between Livorno, Pisa, Florence and Siena, and another in the Reggio Calabria area.

E. De Stefani contributes a specific origin in Friuli: in the Carnia (a mountainous zone of northern Udine province), a family of feudatories bore this surname from at least the second decade of the 14th century in the locality of Siaio (today a frazione of Treppo Ligosullo). In that context, the surname is a Friulian microtoponym, derived from the Friulian scjàle ("staircase, ladder"), and is inserted in the onomastic layer of surnames derived from parts of the house.

R. Brondolo confirms that double semantic orientation —part of the house or sloping geographic feature— and places this origin in northern Italy.