Osaka is about 28 times smaller than Shanghai.

Shanghai is approximately 6,341 sq km, while Osaka is approximately 223 sq km, making Osaka 3.52% the size of Shanghai.
Tip: This to-scale comparison of Shanghai vs. Osaka 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.