Gibraltar is about 27 times smaller than District of Columbia.

District of Columbia is approximately 177 sq km, while Gibraltar is approximately 7 sq km, making Gibraltar 3.67% the size of District of Columbia. Meanwhile, the population of District of Columbia is ~601,723 people (572,150 fewer people live in Gibraltar).
Tip: This to-scale comparison of District of Columbia vs. Gibraltar uses the Mercator projection, which distorts the size of regions near the poles.