Kalaj families are Croats and they are mostly from Zagreb. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Cakovec area. In Vugrišinec in Cakovec area every fourtieth inhabitant had the family name Kalaj.
Prevalence
About 100 people with faimily name Kalaj live in Croatia today, in 40 households. There were 170 of them in the middle of the past century, and their number decreased by 40 percent. They are only located in threee Croatian cities and 5 other places, mostly in Zagreb (35), Odranski Obrez (35), Bratina in Jastrebarsko area (<5), Varazdin (<5), and in Klostar Ivanic in Ivanic-Grad area (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.