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What are the largest counties in California?

Los Angeles County is the largest county in California, with 9,694,934 residents in 2025 (Census PEP). San Diego County (3,282,248) and Orange County (3,149,507) come next.

Data as of 2025 · updated

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All 58 ranked California counties

California counties ranked by population
RankCountyResidents 2025Change 2020–25
1Los Angeles County9,694,934−3.0%
2San Diego County3,282,248−0.6%
3Orange County3,149,507−1.2%
4Riverside County2,544,916+5.0%
5San Bernardino County2,224,091+1.9%
6Santa Clara County1,914,391−0.9%
7Alameda County1,636,630−2.6%
8Sacramento County1,618,460+2.0%
9Contra Costa County1,170,070+0.3%
10Fresno County1,035,456+2.6%
11Kern County927,068+2.3%
12Ventura County830,851−1.5%
13San Francisco County826,079−5.6%
14San Joaquin County823,815+5.5%
15San Mateo County743,568−2.5%
16Stanislaus County557,719+0.7%
17Sonoma County486,444−0.4%
18Tulare County485,146+2.4%
19Solano County455,376+0.5%
20Placer County442,081+8.9%
21Santa Barbara County442,065−1.4%
22Monterey County433,729−1.5%
23Merced County297,260+5.1%
24San Luis Obispo County282,367+0.0%
25Santa Cruz County258,852−4.7%
26Marin County253,694−2.9%
27Yolo County224,410+3.1%
28Butte County209,211−0.5%
29El Dorado County192,323+0.6%
30Shasta County181,648−0.3%
31Imperial County181,411+1.0%
32Madera County167,927+7.4%
33Kings County154,327+1.0%
34Napa County132,949−3.3%
35Humboldt County131,647−3.4%
36Nevada County101,911−0.4%
37Sutter County98,787−0.7%
38Yuba County88,691+8.2%
39Mendocino County88,122−3.5%
40San Benito County70,082+8.6%
41Lake County67,772−0.6%
42Tehama County64,665−1.7%
43Tuolumne County53,160−4.0%
44Calaveras County46,605+2.8%
45Siskiyou County42,013−4.5%
46Amador County41,876+3.2%
47Glenn County28,141−2.6%
48Lassen County28,117−13.1%
49Del Norte County26,410−4.4%
50Colusa County21,836−0.1%
51Plumas County18,583−5.9%
52Inyo County18,158−4.4%
53Mariposa County16,918−1.2%
54Trinity County15,720−2.4%
55Mono County12,505−5.4%
56Modoc County8,426−2.9%
57Sierra County3,098−4.0%
58Alpine County1,043−11.6%

How this is ranked

The Census Bureau's July 1 resident population estimates for 2025, largest first, with the change since 2020. Counties with fewer than 1,000 residents are not ranked. Areas without an estimate for the same year as the others are not ranked.

Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025). Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how ranks and figures are built.

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Questions

What is the largest county in California?

Los Angeles County is the largest county in California, with 9,694,934 residents in 2025 (Census PEP). San Diego County (3,282,248) and Orange County (3,149,507) come next.

How is this ranking calculated?

The Census Bureau's July 1 resident population estimates for 2025, largest first, with the change since 2020. Counties with fewer than 1,000 residents are not ranked. Areas without an estimate for the same year as the others are not ranked.

More rankings for California

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