Atlanta is about 3.9 times bigger than Fort Lauderdale.

Fort Lauderdale (excluding the city's 9.9 sq km of water area) is approximately 90 sq km, while Atlanta is approximately 350 sq km, making Atlanta 289% larger than Fort Lauderdale.
Tip: This to-scale comparison of Fort Lauderdale vs. Atlanta uses the Mercator projection, which distorts the size of regions near the poles.