San Francisco is about 1.7 times smaller than Fremont.

Fremont (map shows its 28 named neighbourhoods; the area covers the whole city) is approximately 202 sq km, while San Francisco (including the city proper only) is approximately 121 sq km, making San Francisco 59.82% the size of Fremont.
Tip: This to-scale comparison of Fremont vs. San Francisco uses the Mercator projection, which distorts the size of regions near the poles.
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