| Zip Code | City | Population ↓ |
|---|---|---|
| 94565 | Pittsburg | 100,826 |
| 94509 | Antioch | 70,889 |
| 94513 | Brentwood | 67,580 |
| 94806 | San Pablo | 63,730 |
| 94553 | Martinez | 49,062 |
| 94582 | San Ramon | 47,338 |
| 94561 | Oakley | 44,546 |
| 94804 | Richmond | 44,387 |
| 94531 | Antioch | 44,115 |
| 94521 | Concord | 41,092 |
| 94583 | San Ramon | 39,758 |
| 94520 | Concord | 36,699 |
| 94523 | Pleasant Hill | 34,964 |
| 94526 | Danville | 33,396 |
| 94801 | Richmond | 32,759 |
| 94549 | Lafayette | 28,456 |
| 94518 | Concord | 28,287 |
| 94803 | El Sobrante | 27,171 |
| 94506 | Danville | 26,947 |
| 94530 | El Cerrito | 26,483 |
| 94598 | Walnut Creek | 26,346 |
| 94547 | Hercules | 26,041 |
| 94596 | Walnut Creek | 23,795 |
| 94597 | Walnut Creek | 23,654 |
| 94519 | Concord | 20,162 |
| 94563 | Orinda | 19,416 |
| 94564 | Pinole | 18,946 |
| 94595 | Walnut Creek | 17,341 |
| 94556 | Moraga | 15,959 |
| 94505 | Discovery Bay | 15,445 |
| 94805 | Richmond | 14,790 |
| 94507 | Alamo | 14,503 |
| 94517 | Clayton | 12,349 |
| 94708 | Berkeley | 11,810 |
| 94572 | Rodeo | 9,309 |
| 94525 | Crockett | 3,599 |
| 94514 | Byron | 2,023 |
| 94511 | Bethel Island | 1,993 |
| 94575 | Moraga | 1,048 |
| 94528 | Diablo | 726 |
| 94548 | Knightsen | 598 |
| 94569 | Port Costa | 251 |
| 94516 | Canyon | 212 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 43 ZCTAs in Contra Costa County, California (US Census).