Strmačka is located in the municipality Cetingrad, in Karlovac County at an elevation of 200 meters above sea level and it covers the area of 1.36 km² (0.53 sq. miles). According to the 2011 census report, there were 23 inhabitants. It is predominantly populated by Croats (93%), but also. Nearby places: Delić Poljana, Kuk, Bilo, Cetinski Varoš, Batnoga, Podcetin, Gornje Gnojnice, Polojski Varoš, Cetingrad and Sadikovac.