Trebež is located in the municipality Jasenovac, in Sisak-Moslavina County at an elevation of 97 meters above sea level and it covers the area of 14.44 km² (5.58 sq. miles). According to the 2011 census report, there were 54 inhabitants. It is entirely populated by Croats. Nearby places: Ivanjski Bok, Puska, Lonja, Crkveni Bok, Kraljeva Velika, Plesmo, Strmen, Suvoj, Sigetac and Krapje.