Jersey City is about 3.2 times smaller than Boston.

Boston is approximately 124 sq km, while Jersey City (map shows its 11 named neighbourhoods; the area covers the whole city) is approximately 38 sq km, making Jersey City 30.8% the size of Boston.
Tip: This to-scale comparison of Boston vs. Jersey City 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.