Guam is about 578 times smaller than New Mexico.

New Mexico is approximately 314,310 sq km, while Guam is approximately 544 sq km, making Guam 0.17% the size of New Mexico. Meanwhile, the population of New Mexico is ~2.1 million people (1.9 million fewer people live in Guam).
Tip: This to-scale comparison of New Mexico vs. Guam uses the Mercator projection, which distorts the size of regions near the poles.