Donji Mekinjar is located in the municipality Udbina, in Lika-Senj County at an elevation of 636 meters above sea level and it covers the area of 33.46 km² (12.92 sq. miles). According to the 2011 census report, there were 35 inhabitants. Nearby places: Tolić, Breštane, Podlapača, Krbava, Rebić, Jošan, Svračkovo Selo, Srednja Gora, Jagodnje and Čojluk.