New York City is 8.7 times larger than Manchester, New Hampshire.
Area: 90 km2 calculated
Manchester is the largest city in the U.S. state of New Hampshire, the tenth largest city in New England, and the largest city in northern New England, an area comprising the states of Maine, New Hampshire, and Vermont. It was first named by the merchant and inventor Samuel Blodget. Wikipedia
Area: 784 km2 calculated
New York is the most populous city in the United States and the center of the New York metropolitan area, the premier gateway for legal immigration to the United States and one of the most populous urban agglomerations in the world. Wikipedia