Lumbardenik is located in the City of Slunj, in Karlovac County at an elevation of 350 meters above sea level and it covers the area of 3.44 km² (1.33 sq. miles). According to the 2011 census report, there were 140 inhabitants. It is predominantly populated by Croats (99%), but also. Nearby places: Donji Popovac, Novo Selo, Gornji Popovac, Jame, Podmelnica, Slunj, Slunjčica, Donji Lađevac, Rastoke and Gornji Kremen.