Madrid is about 3.8 times bigger than San Bernardino.

San Bernardino (map shows its 50 named neighbourhoods; the area covers the whole city) is approximately 161 sq km, while Madrid is approximately 604 sq km, making Madrid 276% larger than San Bernardino.
Tip: This to-scale comparison of San Bernardino vs. Madrid uses the Mercator projection, which distorts the size of regions near the poles.
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