Kosmač families are Croats and they are mostly from Koprivnica. In the past century, relatively most of Croatian residents bearing this family name were born in Karlovac and Zagreb.
Prevalence
About 60 people with faimily name Kosmač live in Croatia today, in 30 households. There were 80 of them in the middle of the past century, and their number decreased by 20 percent. They are located in 8 Croatian counties, in 9 cities and 12 other places, mostly in Koprivnica (10), Senkovec in Cakovec area (<10), Zagreb (<10), Karlovac (<10), and in Dvorisce Ozaljsko (<10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1928 in source Emigration Commission Zagreb.