Koštan families are Croats and they are mostly from Sibenik. In the past century, relatively most of Croatian residents bearing this family name were born in Sibenik and Zagreb.
Prevalence
About 120 people with faimily name Koštan live in Croatia today, in 40 households. There were 120 of them in the middle of the past century, and their number remains constant. They are located in 8 Croatian counties, in 9 cities and four other places, mostly in Sibenik (55), Zagreb (15), Konjevrate (15), Split (<5), and in Matulji in Opatija area (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.