Cocos (Keeling) Islands is about 28,849 times smaller than California.

California is approximately 403,882 sq km, while Cocos (Keeling) Islands is approximately 14 sq km, making Cocos (Keeling) Islands 0.0% the size of California. Meanwhile, the population of California is ~37.3 million people (37.3 million fewer people live in Cocos (Keeling) Islands).
Tip: This to-scale comparison of California vs. Cocos (Keeling) Islands uses the Mercator projection, which distorts the size of regions near the poles.