Tvrda Reka is located in the municipality Kapela, in Bjelovar-Bilogora County at an elevation of 180 meters above sea level and it covers the area of 5.69 km² (2.20 sq. miles). According to the 2011 census report, there were 29 inhabitants. It is predominantly populated by Croats (90%), but also Serbs (10%). Nearby places: Jakopovac, Pavlin Kloštar, Reškovci, Prnjavor, Domankuš, Lipovčani, Sredice Gornje, Visovi, Lalići and Zrinski Topolovac.