Birmingham is about 3.1 times bigger than Boston.

Boston is approximately 124 sq km, while Birmingham (map shows its 87 named neighbourhoods; the area covers the whole city) is approximately 381 sq km, making Birmingham 207% larger than Boston.
Tip: This to-scale comparison of Boston vs. Birmingham 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.