Castro Valley, CA ZIP Codes
Castro Valley, California has 3 ZIP codes: 3 for street addresses (, and ).
Your street decides which one you use.
Which Castro Valley ZIP code is my address in?
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?
Castro Valley ZIP code map
Tap or point to an area to see its ZIP code.Full-size map
Dashed line: the Castro Valley Census outline.
Map: Census Bureau ZIP Code Tabulation Areas (2020) and place limits (2024).
All Castro Valley ZIP codes by type
| ZIP | Type and post office or station |
|---|---|
| 94546 | street delivery Castro Valley |
| 94552 | street delivery Castro Valley |
| 94578 | street delivery; mail may be addressed to San Leandro South San Leandro |
Why your mail may say Castro Valley when you live outside it
Castro Valley ZIP codes also cover Union City and Ashland, so a letter addressed to Castro Valley can go to a home outside the town.
A ZIP code does not set your city, school district or tax. Alameda County property records show which city you are in.
Castro Valley ZIP code questions
What is the main ZIP code for Castro Valley?
94546, the ZIP code of the main Castro Valley post office at 20283 Santa Maria Ave.
What county is Castro Valley in?
Alameda County.
ZIP codes for towns near Castro Valley
More towns near Castro Valley: Oakland, Pleasanton, Alameda, Walnut Creek, Newark, Foster City, Redwood City, Fremont, Menlo Park.
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