Las Vegas is about 4.1 times bigger than Fort Lauderdale.

Fort Lauderdale (excluding the city's 9.9 sq km of water area) is approximately 90 sq km, while Las Vegas is approximately 367 sq km, making Las Vegas 308% larger than Fort Lauderdale.
Tip: This to-scale comparison of Fort Lauderdale vs. Las Vegas uses the Mercator projection, which distorts the size of regions near the poles.