Brooklyn (NYC borough) is 3.1 times larger than Manhattan (NYC borough).
Area: 180 km2 calculated
Population: 2,565,635 (2012)
Brooklyn is the most populous of New York City's five boroughs, with about 2.6 million people, as well as the second-largest in area. Wikipedia
Area: 59 km2 calculated
Population: 1,619,090 (2012)
Manhattan is the most densely populated of the five boroughs of New York City. The borough is coterminous with New York County, an original county of the U.S. state of New York. Wikipedia