Montserrat is about 1.7 times smaller than District of Columbia.

District of Columbia is approximately 177 sq km, while Montserrat is approximately 102 sq km, making Montserrat 57.63% the size of District of Columbia. Meanwhile, the population of District of Columbia is ~601,723 people (596,309 fewer people live in Montserrat).
Tip: This to-scale comparison of District of Columbia vs. Montserrat uses the Mercator projection, which distorts the size of regions near the poles.