The largest county in California
There are two right answers. By land area it is San Bernardino County; by population it is Los Angeles County. Which one you want depends on what you meant by largest.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025. Retrieved 30 August 2026.
By land area
| Rank | Name | Land area | Population |
|---|---|---|---|
| 1 | San Bernardino County | 20,068 sq mi | 2,224,091 |
| 2 | Inyo County | 10,197 sq mi | 18,158 |
| 3 | Kern County | 8,135 sq mi | 927,068 |
| 4 | Riverside County | 7,209 sq mi | 2,544,916 |
| 5 | Siskiyou County | 6,279 sq mi | 42,013 |
| 6 | Fresno County | 5,959 sq mi | 1,035,456 |
| 7 | Tulare County | 4,824 sq mi | 485,146 |
| 8 | Lassen County | 4,541 sq mi | 28,117 |
| 9 | San Diego County | 4,211 sq mi | 3,282,248 |
| 10 | Imperial County | 4,175 sq mi | 181,411 |
By population
| Rank | Name | Population | Density |
|---|---|---|---|
| 1 | Los Angeles County | 9,694,934 | 2,388 per sq mi |
| 2 | San Diego County | 3,282,248 | 779 per sq mi |
| 3 | Orange County | 3,149,507 | 3,970 per sq mi |
| 4 | Riverside County | 2,544,916 | 353 per sq mi |
| 5 | San Bernardino County | 2,224,091 | 111 per sq mi |
| 6 | Santa Clara County | 1,914,391 | 1,483 per sq mi |
| 7 | Alameda County | 1,636,630 | 2,219 per sq mi |
| 8 | Sacramento County | 1,618,460 | 1,677 per sq mi |
| 9 | Contra Costa County | 1,170,070 | 1,632 per sq mi |
| 10 | Fresno County | 1,035,456 | 174 per sq mi |
And the smallest
More on California
Rebuilt from source data 30 August 2026. How these figures are produced.