Contra Costa County, California has 52 ZIP codes in this list, from 94505 to 94850. They cover 30 places, among them Concord, Richmond, Walnut Creek and Moraga.
The ZIP code areas of Contra Costa County add up to about 622 square miles of land (1,611 sq km) as the Census Bureau draws them. The largest is 94513 (Brentwood), with 78.9 square miles.
Places with more than one code here: Concord (8 codes), Richmond (7 codes), Walnut Creek (4 codes).
Using these codes
In an address, the ZIP code comes last, after the city and the two-letter state: Discovery Bay, CA 94505.
Tap a ZIP code to open it in the look-up, with a copy button for the address line.
A code can cross a county line, and one town can have several codes. The table shows the main place of each code.
"No area" means the Census Bureau draws no area for that code. Such codes are usually for post office boxes or a single building.
Places and counties: GeoNames. Areas: U.S. Census Bureau, 2024 ZIP Code Tabulation Areas. Checked in November 2026. This site is not connected with the United States Postal Service; for mailing, confirm the address with USPS.
ZIP Codes