Detroit is 3.7% larger than Philadelphia.
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
Area: 383 km2 calculated
Detroit is the most populous city in the U.S. state of Michigan and the largest city on the United States-Canada border. It is the seat of Wayne County, the most populous county in the state. Wikipedia