Kansas City is about 3.1 times smaller 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 Kansas City (map shows its 145 named neighbourhoods; the area covers the whole city) is approximately 815 sq km, making Kansas City 31.8% the size of Moscow.
Tip: This to-scale comparison of Moscow vs. Kansas City uses the Mercator projection, which distorts the size of regions near the poles.
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