Philadelphia is 6.3 times larger than Manhattan (NYC borough).
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
Area: 370 km2 calculated
Philadelphia is the largest city in the Commonwealth of Pennsylvania, the fifth-most-populous city in the United States, and the core of the sixth-largest metropolitan area in the country. Wikipedia