Hartje is located in the municipality Žumberak, in Zagreb County at an elevation of 597 meters above sea level and it covers the area of 2.75 km² (1.06 sq. miles). According to the 2011 census report, there were 32 inhabitants. It is entirely populated by Croats. Nearby places: Petričko Selo, Grgetići, Kalje, Grič, Tomaševci, Gornja Vas, Drašći Vrh, Javor, Višći Vrh and Željezno Žumberačko.