Ivaci families are Croats and they are mostly from Prelog area. In the past century, relatively most of Croatian residents bearing this family name were born in Prelog area and in Zagreb.
Prevalence
About 70 people with faimily name Ivaci live in Croatia today, in 30 households. There were 30 of them in the middle of the past century, and their number more than doubled. They are located in four Croatian counties and 7 other places, mostly in Zagreb (30), Velika Gorica (15), Sveta Marija in Prelog area (10), Cakovec (<10), and in Donji Mihaljevec in Prelog area (<5).
Outside Croatia
At least four families with this surname emigrated from Croatia to: the United States (2), Germany (1), and to Austria (1). Family name Ivaci (including: Ivachi , Iwazi ) is present in four countries on three continents. "Iwazi " is used by few people in the United States.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.