Seattle is about 2.4 times bigger than Fort Lauderdale.

Fort Lauderdale (excluding the city's 9.9 sq km of water area) is approximately 90 sq km, while Seattle is approximately 217 sq km, making Seattle 141% larger than Fort Lauderdale.
Tip: This to-scale comparison of Fort Lauderdale vs. Seattle uses the Mercator projection, which distorts the size of regions near the poles.