District of Columbia is about 4.1 times smaller than Singapore.

Singapore is approximately 719 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 24.61% the size of Singapore. Meanwhile, the population of Singapore is ~5.9 million people (5.3 million fewer people live in District of Columbia).
Tip: This to-scale comparison of Singapore vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.
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