Kazlu Ruda's 2026 population is now estimated at 5,413. In 1989, the population of Kazlu Ruda was 7,715. Kazlu Ruda experienced a decrease of -35 residents over the past year, marking an annual decline of -0.64%. These population values and projections come from Lithuania city census rows via CityPopulation official attribution, Lithuania 2021 census city subset (direct official ArcGIS service), World Population Review Internal Projections and Lithuania city estimate rows via CityPopulation official attribution .