District of Columbia is about 1.5 times smaller than Saint Kitts and Nevis.

Saint Kitts and Nevis is approximately 261 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 67.82% the size of Saint Kitts and Nevis. Meanwhile, the population of Saint Kitts and Nevis is ~54,488 people (547,235 more people live in District of Columbia).
Tip: This to-scale comparison of Saint Kitts and Nevis vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.