Los Angeles County, California is 5.3 times larger than Jacksonville, Florida.
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
Area: 10,580 km2 calculated
Los Angeles County, also known as L.A. County, officially the County of Los Angeles, is a county in the U.S. state of California. As of the 2010 U.S. Census, the county has a population of 9,818,605, making it the most populous county in the United States. Wikipedia