Sydney is about 3.4 times smaller than Missoula.

Missoula (map shows its 17 named neighbourhoods; the area covers the whole city) is approximately 91 sq km, while Sydney is approximately 27 sq km, making Sydney 29.43% the size of Missoula.
Tip: This to-scale comparison of Missoula vs. Sydney 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.