Fort Lauderdale is about 4.1 times smaller than Las Vegas.

Las Vegas is approximately 367 sq km, while Fort Lauderdale (excluding the city's 9.9 sq km of water area) is approximately 90 sq km, making Fort Lauderdale 24.5% the size of Las Vegas.
Tip: This to-scale comparison of Las Vegas vs. Fort Lauderdale uses the Mercator projection, which distorts the size of regions near the poles.