State size comparison
Illinois is about 2.8 times smaller than California.
California is approximately 403,882 sq km, while Illinois is approximately 143,961 sq km, making Illinois 35.64% the size of California. Meanwhile, the population of California is ~37.3 million people (24.4 million fewer people live in Illinois).
This to-scale comparison of California vs. Illinois uses the Mercator projection, which distorts the size of regions near the poles. Learn more. Note: Try dragging the outline to reposition.