Lonjak families are Croats and they are mostly from Lepoglava area. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Lepoglava area.
Prevalence
About 110 people with faimily name Lonjak live in Croatia today, in 40 households. There were 130 of them in the middle of the past century, and their number decreased by 20 percent. They are located in 10 Croatian counties, in 12 cities and 12 other places, mostly in Zagreb (30), Varazdin (25), Vrbno in Lepoglava area (15), Koprivnica (10), and in Osijek (<10).
Outside Croatia
Family name Lonjak (including: Loniak , Lonyak ) is present in 10 countries on two continents. The family name "Lonjak " is used by small number of people in the United States. "Loniak " is used by small number of people in the United States , small number in Ukraine , and small number of people in Germany.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.