Iran is about 4.1 times bigger than California.

California is approximately 403,882 sq km, while Iran is approximately 1,648,195 sq km, making Iran 308% larger than California. Meanwhile, the population of California is ~37.3 million people (49.5 million more people live in Iran).
Tip: This to-scale comparison of California vs. Iran uses the Mercator projection, which distorts the size of regions near the poles.