Sydney is about 3.9 times smaller than Red Deer.

Red Deer (map shows its 83 named neighbourhoods; the area covers the whole city) is approximately 105 sq km, while Sydney is approximately 27 sq km, making Sydney 25.49% the size of Red Deer.
Tip: This to-scale comparison of Red Deer 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.