Los Angeles County, California is 100 times larger than Fontana, California.
Area: 106 km2 calculated
Fontana is a city of 200,762 residents in San Bernardino County, California. Founded by Azariel Blanchard Miller in 1913, it remained essentially rural until World War II, when entrepreneur Henry J. Kaiser built a large steel mill in the area. 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