In Croatia, Kogaj families are Croats (from Krapina area ). In the past century, relatively most of Croatian residents bearing this family name were born in Krapina area and in Krapina.
Prevalence
About 10 people with faimily name Kogaj live in Croatia today, in three households only. They are located in only threee Croatian places: in Velika Ves (<10), Zagreb (<5), and in Kraljevec Semnicki in Krapina area (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over five times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.