New York City is about 4.9 times smaller than Sydney.

Sydney (the 30 councils of metropolitan Sydney, without the Blue Mountains, Hawkesbury, Wollondilly and the Central Coast) is approximately 3,810 sq km, while New York City (including all five boroughs: Manhattan, Brooklyn, Queens, The Bronx, and Staten Island) is approximately 781 sq km, making New York City 20.5% the size of Sydney.
Tip: This to-scale comparison of Sydney vs. New York City uses the Mercator projection, which distorts the size of regions near the poles.
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