Montserrat is about 3,081 times smaller than New Mexico.

New Mexico is approximately 314,310 sq km, while Montserrat is approximately 102 sq km, making Montserrat 0.03% the size of New Mexico. Meanwhile, the population of New Mexico is ~2.1 million people (2.1 million fewer people live in Montserrat).
Tip: This to-scale comparison of New Mexico vs. Montserrat uses the Mercator projection, which distorts the size of regions near the poles.