District of Columbia is about 143 times smaller than Maryland.

Maryland is approximately 25,314 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 0.7% the size of Maryland. Meanwhile, the population of Maryland is ~5.8 million people (5.2 million fewer people live in District of Columbia).
Tip: This to-scale comparison of Maryland vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.