Miami is about 2.4 times bigger than Jersey City.

Jersey City (map shows its 11 named neighbourhoods; the area covers the whole city) is approximately 38 sq km, while Miami is approximately 92 sq km, making Miami 142% larger than Jersey City.
Tip: This to-scale comparison of Jersey City vs. Miami 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.