California is about 1.3 times bigger than Oman.

Oman is approximately 309,500 sq km, while California is approximately 403,882 sq km, making California 30% larger than Oman. Meanwhile, the population of Oman is ~5.5 million people (33.9 million more people live in California).
Tip: This to-scale comparison of Oman vs. California uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.