Tulsa, Oklahoma is 2.4 times larger than Des Moines, Iowa.
Area: 235 km2 calculated
Des Moines is the capital and the most populous city in the U.S. state of Iowa. It is also the county seat of Polk County. A small portion of the city extends into Warren County. It was incorporated on September 22, 1851, as Fort Des Moines which was shortened to "Des Moines" in 1857. Wikipedia
Area: 569 km2 calculated
Tulsa is the second-largest city in the U.S. state of Oklahoma and 46th-largest city in the United States. The population has grown since the 2010 census, With a population of 398,121 as of July 2013. Wikipedia