Boise is about 29 times smaller than Shanghai.

Shanghai is approximately 6,341 sq km, while Boise is approximately 221 sq km, making Boise 3.48% the size of Shanghai.
Tip: This to-scale comparison of Shanghai vs. Boise 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.