San Bernardino, California is 2.4 times larger than Boulder, Colorado.
Area: 68 km2 calculated
Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of 5,430 feet. The city is 25 miles northwest of Denver. Wikipedia
Area: 159 km2 calculated
San Bernardino is a city located in the Riverside-San Bernardino metropolitan area. It serves as the county seat of San Bernardino County, California, United States. Wikipedia