Columbus, Ohio is 3.9 times larger than Washington, D.C..
Area: 694 km2 calculated
Columbus is the capital of and the largest city in the U.S. state of Ohio. It is the 15th largest city in the United States with a population of 822,553. It is the core city of the Columbus, OH Metropolitan Statistical Area, which encompasses a ten county area. Wikipedia
Area: 178 km2 calculated
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. Wikipedia