Luxembourg is about 3 times smaller than French Southern and Antarctic Lands.

French Southern and Antarctic Lands is approximately 7,829 sq km, while Luxembourg is approximately 2,586 sq km, making Luxembourg 33.03% the size of French Southern and Antarctic Lands.
Tip: This to-scale comparison of French Southern and Antarctic Lands vs. Luxembourg uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: Luxembourg vs. French Southern and Antarctic Lands