British Indian Ocean Territory is about 6,731 times smaller than California.

California is approximately 403,882 sq km, while British Indian Ocean Territory is approximately 60 sq km, making British Indian Ocean Territory 0.01% the size of California. Meanwhile, the population of California is ~39.4 million people (39.4 million fewer people live in British Indian Ocean Territory).
Tip: This to-scale comparison of California vs. British Indian Ocean Territory uses the Mercator projection, which distorts the size of regions near the poles.

Compare further: British Indian Ocean Territory vs. California

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