Austin, Texas is 2.6 times larger than Las Vegas.
Area: 933 km2 calculated
Austin is the capital of Texas and the seat of Travis County. Located in Central Texas and the American Southwest, it is the 11th-most populous city in the United States of America and the fourth-most populous city in the state of Texas. Wikipedia
Area: 363 km2 calculated
Las Vegas, officially the City of Las Vegas and often known as simply Vegas, is the most populous city in the state of Nevada and the county seat of Clark County. Wikipedia