Guam is about 4.8 times smaller than Luxembourg.

Luxembourg is approximately 2,586 sq km, while Guam is approximately 544 sq km, making Guam 21.04% the size of Luxembourg. Meanwhile, the population of Luxembourg is ~686,970 people (517,971 fewer people live in Guam).
Tip: This to-scale comparison of Luxembourg vs. Guam uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.