Tokyo is about 1.4 times smaller than San Diego.

San Diego is approximately 844 sq km, while Tokyo is approximately 619 sq km, making Tokyo 73.34% the size of San Diego.
Tip: This to-scale comparison of San Diego vs. Tokyo 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.