Foster City, CA ZIP Code
Foster City, California has one ZIP code: .
Mail addressed to Foster City covers nearby places too.
Where the 94404 ZIP code reaches
Tap or point to an area to see its ZIP code.Full-size map
Dashed line: Foster City city limits.
Map: Census Bureau ZIP Code Tabulation Areas (2020) and place limits (2024).
Check an address in Foster City
Street ranges from the Census Bureau, 2026. PO box and organization ZIP codes are not found by street. A new street may be missing: address not found?
Foster City ZIP code questions
What is the main ZIP code for Foster City?
94404, the ZIP code of the main Foster City post office at 750 Alma Ln Suite 100.
What county is Foster City in?
San Mateo County.
ZIP codes for towns near Foster City
More towns near Foster City: San Leandro, San Bruno, Alameda, Newark, Union City, Pacifica, Palo Alto, Oakland, Castro Valley.
Sources and last checked
USPS ZIP Locale Detail (October 1, 2026), GeoNames (CC BY 4.0), U.S. Census Bureau, HUD-USPS crosswalk.
Checked October 20, 2026. Sources · How we build our lists · Corrections