Trosa is a municipality in central Sweden, in the county of Södermanland. The municipality covers an area of 207.9 km². Of the total population of 10197, 5105 are male, and 5092 are female. The population density of the community is 49 inhabitants per km².
... size is 2.45 and the average family size is 3.00.
In the town the population is spread out with 13.8% under the age of 18, 34.0% from 18 to 24, 17.6% from 25 to 44, ...