Boston is 2.2 times larger than Manhattan (NYC borough).
Area: 129 km2 calculated
Boston is the capital and largest city of the Commonwealth of Massachusetts in the United States. Boston also serves as county seat of Suffolk County. Wikipedia
Area: 59 km2 calculated
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