Chicago is about 2.6 times smaller than Sao Paulo.

Sao Paulo is approximately 1,523 sq km, while Chicago is approximately 590 sq km, making Chicago 38.73% the size of Sao Paulo.
Tip: This to-scale comparison of Sao Paulo vs. Chicago 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.