Missoula is about 1.4 times smaller than Boston.

Boston is approximately 124 sq km, while Missoula (map shows its 17 named neighbourhoods; the area covers the whole city) is approximately 91 sq km, making Missoula 73.16% the size of Boston.
Tip: This to-scale comparison of Boston vs. Missoula 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.