Philadelphia is 7.9 times larger than Allentown, Pennsylvania.
Area: 47 km2 calculated
Allentown is a city located in Lehigh County, Pennsylvania, United States. It is Pennsylvania's third most populous city, after Philadelphia and Pittsburgh, and the 224th largest city in the United States. 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