Germany's population is projected to increase by just 0.6% by 2040, according to an analysis released on Tuesday.
The study presented by the Bertelsmann Foundation said that population growth will be unevenly distributed across Germany's individual federal states.
While Saarland and the eastern states have to plan for population declines compared to 2020, the authors forecast an increase for the other states.
According to the calculations, the population change in Germany's 13 non-city states by 2040 ranges from plus 4.6% in the south-western state of Baden-Württemberg to minus 12.3% in the eastern German state of Saxony-Anhalt.
In the city states of Berlin and Hamburg, the study projected a significant increase of 5.8% and 3.5% respectively, while Bremen was projected to see a moderate increase of 1.1% compared to 2020.
According to the Federal Statistical Office, 83.15 million people lived in Germany in 2020.
The forecasts are based on births, deaths and migration.