San Francisco is about 11 times smaller than San Antonio.

San Antonio (map shows its 401 named neighbourhoods; the area covers the whole city) is approximately 1,292 sq km, while San Francisco (including the city proper only) is approximately 121 sq km, making San Francisco 9.36% the size of San Antonio.
Tip: This to-scale comparison of San Antonio vs. San Francisco uses the Mercator projection, which distorts the size of regions near the poles.
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