Nantucket is about 1.6 times smaller than Catalina Island.

Catalina Island is approximately 194 km² (75 sq mi), while Nantucket is approximately 124 km² (48 sq mi), making Nantucket 63.75% the size of Catalina Island.
Tip: This to-scale comparison of Catalina Island vs. Nantucket 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.