District of Columbia is about 2,282 times smaller than California.

California is approximately 403,882 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 0.04% the size of California. Meanwhile, the population of California is ~37.3 million people (36.7 million fewer people live in District of Columbia).
Tip: This to-scale comparison of California vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.