Sydney is about 15 times bigger than Sacramento.

Sacramento is approximately 253 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 1,406% larger than Sacramento.
Tip: This to-scale comparison of Sacramento vs. Sydney uses the Mercator projection, which distorts the size of regions near the poles.
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