Sydney is about 1.5 times bigger than Moscow.

Moscow (map shows its 125 districts within the pre-2012 boundary; the area includes New Moscow) is approximately 2,562 sq km, while Sydney (the 30 councils of metropolitan Sydney, without the Blue Mountains, Hawkesbury, Wollondilly and the Central Coast) is approximately 3,810 sq km, making Sydney 49% larger than Moscow.
Tip: This to-scale comparison of Moscow vs. Sydney uses the Mercator projection, which distorts the size of regions near the poles.
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