How big is Manhattan Island? July 8, 2020 by Pamela Landy Manhattan is 13.4 miles long, 2.3 miles across at its widest point, and 22.5 square miles in area. Related Answers Who was the first golfer to win the prestigious grand slam? What was future mayor of New York City Fiorello La Guardia’s job at Ellis Island? In what American cities were the following world’s fairs held? Is it true that Manhattan Island was bought from the Indians for $24? What is the name of Dr. No’s island in Dr. No (1962)? Who wrote “The Ballad of Gilligan’s Island” for the TV series?