San Bernardino is about 10 times smaller than London.

London (including the 32 boroughs of greater London) is approximately 1,572 sq km, while San Bernardino (map shows its 50 named neighbourhoods; the area covers the whole city) is approximately 161 sq km, making San Bernardino 10.23% the size of London.
Tip: This to-scale comparison of London vs. San Bernardino uses the Mercator projection, which distorts the size of regions near the poles.
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