Duvnjak families are usually Croats and they are mostly from Blato na Cetini. According to some sources they are from Tomislavgrad area and Vrlika area (Garjak), very rarely Serbs. In the past century, relatively most of Croatian residents bearing this family name were born in Western Bosnia (Livno area) and in Bosnian Krajina (Sipovo area). In Čuklić in Bosnian Krajina every second inhabitant had the family name Duvnjak.
Prevalence
About 1900 people with faimily name Duvnjak live in Croatia today, in 720 households. There were 430 of them in the middle of the past century, and their number multiplied. They are located in all Croatian counties, in 67 cities and 143 other places, mostly in Zagreb (305), Djakovo (155), Solin (100), Split (95), and in Koska in Nasice area (65).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 2007 in source Encyclopaedia of Croatian Surnames.