Trnovica is located in the municipality Dubrovačko Primorje, in Dubrovnik-Neretva County at an elevation of 300 meters above sea level and it covers the area of 12.40 km² (4.79 sq. miles). According to the 2011 census report, there were 38 inhabitants. It is entirely populated by Croats. Nearby places: Točionik, Čepikuće, Visočani, Lisac, Podgora, Zamaslina, Smokovljani, Podimoć, Mravnica and Ošlje.