Jacksonville, Florida is 13 times larger than Dayton, Ohio.
Area: 149 km2 calculated
Dayton is the sixth largest city in the U.S. state of Ohio and is the county seat of Montgomery County. Wikipedia
Area: 1,988 km2 calculated
Jacksonville is the largest city in the U.S. state of Florida by population and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968. Wikipedia