ZIP Codes in Antioch, CA
Antioch uses 2 ZIP codes, all in Contra Costa County. Pick one below for details, or look up the full nine-digit ZIP+4 for a specific street address.
All 2 Antioch ZIP codes
| ZIP | Type | County | Population |
|---|---|---|---|
| 94509 | standard | Contra Costa | 70,090 |
| 94531 | standard | Contra Costa | 46,387 |
Finding a ZIP+4 in Antioch
Knowing which of these 2 ZIP codes covers an address only gets you partway. The four-digit extension identifies the specific delivery point — typically one side of one block. Two houses facing each other on the same Antioch street almost always have different ZIP+4 codes even though they share all five leading digits.
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