Skupnjak families are Croats and they are mostly from Varazdin area. In the past century, relatively most of Croatian residents bearing this family name were born in Varazdin and in Varazdin area. In Žabnjak in Vrbovec area every seventh inhabitant had the family name Skupnjak.
Prevalence
About 460 people with faimily name Skupnjak live in Croatia today, in 170 households. There were 400 of them in the middle of the past century, and their number increased by 10 percent. They are located in the most of Croatian counties, in 19 cities and 37 other places, mostly in Trnovec (185) and Bartolovec (55) in Varazdin area, Varazdin (45), Zagreb (20), and in Sesvete (15).
Outside Croatia
Family name Skupnjak is present in 7 countries on four continents. The family name "Skupnjak " is used by small number of people in the United States and small number in Uruguay.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over five times, the first time 2007 in source Encyclopaedia of Croatian Surnames.