In Croatia, Koler families are predominantly Croats (from Buzet area ), very rarely Czechs (from Daruvar area ), and . In the past century, relatively most of Croatian residents bearing this family name were born in Daruvar area and in Pakrac.
Prevalence
About 50 people with faimily name Koler live in Croatia today, in 30 households. There were 140 of them in the middle of the past century, and their number decreased significantly. They are located in 9 Croatian counties, in 13 cities and 10 other places, mostly in Sirac in Daruvar area (<10), Bilje in Osijek area (<10), Brkac in Buzet area (<10), Zagreb (<5), and in Beli Manastir (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over twenty times, the first time 1917 in source List of Dignitaries, Officials and Public Servants of the Kingdom of Croatia-Slavonia.