San Francisco is about 1.9 times smaller than Des Moines.

Des Moines (map shows its 58 named neighbourhoods; the area covers the whole city) is approximately 228 sq km, while San Francisco (including the city proper only) is approximately 121 sq km, making San Francisco 52.99% the size of Des Moines.
Tip: This to-scale comparison of Des Moines vs. San Francisco uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.