Chicago is about 2.3 times smaller than Brisbane.

Brisbane is approximately 1,343 sq km, while Chicago is approximately 590 sq km, making Chicago 43.93% the size of Brisbane.
Tip: This to-scale comparison of Brisbane 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.