California is about 1,711 times bigger than Cook Islands.

Cook Islands is approximately 236 sq km, while California is approximately 403,882 sq km, making California 171,036% larger than Cook Islands. Meanwhile, the population of Cook Islands is ~8,128 people (37.2 million more people live in California).
Tip: This to-scale comparison of Cook Islands vs. California uses the Mercator projection, which distorts the size of regions near the poles.