Ranking of California Counties By Population in 2021
Updated on June 18, 2025.
Based on the US Census Vintage data estimates, in 2021, the Population for California was 39.14M. Among all California counties, Los Angeles County had the highest population (9.81M), followed by San Diego County (3.27M), and Orange County (3.16M).
The chart below shows the top 10 counties, and the table below shows the ranking of all California counties.
You can see similar ranking information for related topics, and for other states. You can also see the ranking of all counties in the United States.
Related Topics: California Census Vintage Data Topic List.
Data Source: US Census Bureau (Vintage), 2021 Census.
See this for other years:
Ranking of California Counties By Population in 2021
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| Rank | County | Population |
|---|---|---|
| 1 | Los Angeles County | 9809239 |
| 2 | San Diego County | 3274244 |
| 3 | Orange County | 3159351 |
| 4 | Riverside County | 2455225 |
| 5 | San Bernardino County | 2190877 |
| 6 | Santa Clara County | 1878320 |
| 7 | Alameda County | 1643856 |
| 8 | Sacramento County | 1588824 |
| 9 | Contra Costa County | 1163813 |
| 10 | Fresno County | 1012879 |
| 11 | Kern County | 912782 |
| 12 | Ventura County | 840009 |
| 13 | San Francisco County | 815498 |
| 14 | San Joaquin County | 788096 |
| 15 | San Mateo County | 739330 |
| 16 | Stanislaus County | 552939 |
| 17 | Sonoma County | 484561 |
| 18 | Tulare County | 476939 |
| 19 | Solano County | 450819 |
| 20 | Monterey County | 439245 |
| 21 | Santa Barbara County | 437117 |
| 22 | Placer County | 412968 |
| 23 | Merced County | 284834 |
| 24 | San Luis Obispo County | 279468 |
| 25 | Santa Cruz County | 260904 |
| 26 | Marin County | 259254 |
| 27 | Yolo County | 213545 |
| 28 | Butte County | 206351 |
| 29 | El Dorado County | 193724 |
| 30 | Shasta County | 182243 |
| 31 | Imperial County | 179206 |
| 32 | Madera County | 159019 |
| 33 | Kings County | 152724 |
| 34 | Napa County | 136219 |
| 35 | Humboldt County | 134978 |
| 36 | Nevada County | 103499 |
| 37 | Sutter County | 99121 |
| 38 | Mendocino County | 91303 |
| 39 | Yuba County | 83035 |
| 40 | Lake County | 68623 |
| 41 | San Benito County | 66703 |
| 42 | Tehama County | 65467 |
| 43 | Tuolumne County | 55126 |
| 44 | Calaveras County | 46262 |
| 45 | Siskiyou County | 44144 |
| 46 | Amador County | 41245 |
| 47 | Lassen County | 31884 |
| 48 | Glenn County | 28714 |
| 49 | Del Norte County | 27581 |
| 50 | Colusa County | 21931 |
| 51 | Plumas County | 19965 |
| 52 | Inyo County | 18920 |
| 53 | Mariposa County | 17136 |
| 54 | Trinity County | 16102 |
| 55 | Mono County | 13263 |
| 56 | Modoc County | 8640 |
| 57 | Sierra County | 3298 |
| 58 | Alpine County | 1203 |