Justament families are Croats and they are mostly from Ivanec. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and Ivanec.
Prevalence
About 110 people with faimily name Justament live in Croatia today, in 40 households. There were 50 of them in the middle of the past century, and their number doubled. They are located in the most of Croatian counties, in 10 cities and 8 other places, mostly in Punikve (35), Zagreb (25), Zapresic (15), Karlovac (<10), and in Cres on the Island of Cres (<10).
Outside Croatia
Family name Justament is present in this form only in Croatia.
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.