Monaco is about 88 times smaller than District of Columbia.

District of Columbia is approximately 177 sq km, while Monaco is approximately 2 sq km, making Monaco 1.13% the size of District of Columbia. Meanwhile, the population of District of Columbia is ~601,723 people (570,323 fewer people live in Monaco).
Tip: This to-scale comparison of District of Columbia vs. Monaco uses the Mercator projection, which distorts the size of regions near the poles.