Singapore is 4.6 times larger than Pittsburgh.
Area: 697 km2 World Factbook
Population: 5,567,301 (July 2014) World Factbook
Singapore, officially the Republic of Singapore, is a sovereign city-state and island country in Southeast Asia. It lies off the southern tip of the Malay Peninsula and is 137 kilometres north of the equator. Wikipedia
Area: 153 km2 calculated
Pittsburgh is the seat of Allegheny County and with a population of 305,841 is the second-largest city in the U.S. state of Pennsylvania. With a metropolitan CSA population of 2,659,937, it is the largest in both the Ohio Valley and Appalachia and the 20th-largest in the U.S. Wikipedia