Manhattan is about 3.6 times smaller than Catalina Island.

Catalina Island is approximately 194 km² (75 sq mi), while Manhattan is approximately 55 km² (21 sq mi), making Manhattan 28.09% the size of Catalina Island.
Tip: This to-scale comparison of Catalina Island vs. Manhattan 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.