The population in Sörmland, Sweden, decreased by 1,102 people at the turn of the year compared to 2024, totaling 300,440 residents. Strängnäs was the only municipality in the region with a population increase, adding 74 people to reach 39,387. Births in Sörmland fell to 2,469 in 2025, 101 fewer than the previous year, marking the lowest level since 2000.
Across Sweden, the population grew by 17,819 to 10,605,529, while the number of births nationwide declined for the fourth consecutive year. Population changes in Sörmland municipalities included decreases in Eskilstuna by 414, Flen by 267, and Katrineholm by 170, among others.