Trošmarija is located in the City of Ogulin, in Karlovac County at an elevation of 160 meters above sea level and it covers the area of 10.46 km² (4.04 sq. miles). According to the 2011 census report, there were 123 inhabitants. It is mostly populated by Croats (74%), but also Serbs (24%). Nearby places: Otok na Dobri, Popovo Selo, Malik, Mateše, Grabrk, Gornje Dubrave, Podumol, Soline, Umol and Duga Gora.