Philadelphia is 74% larger than Baltimore.
Area: 212 km2 calculated
Baltimore is the largest city in the U.S. state of Maryland and the 26th-most populous city in the country. It is located in the central area of the state along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. 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