District of Columbia is about 22 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 District of Columbia is approximately 177 sq km, making District of Columbia 4.65% the size of Sydney.
Tip: This to-scale comparison of Sydney vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.
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