18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| San Diego | 1 | 1,409,359 | 1,384,824 | 0.35% | 4,323 | 326 | City |
| Chula Vista | 2 | 279,230 | 275,808 | 0.25% | 5,625 | 50 | City |
| Oceanside | 3 | 170,158 | 174,071 | -0.46% | 4,123 | 41 | City |
| Escondido | 4 | 148,297 | 151,045 | -0.37% | 3,971 | 37 | City |
| Carlsbad | 5 | 113,236 | 114,930 | -0.3% | 2,995 | 38 | City |
| El Cajon | 6 | 102,592 | 106,087 | -0.68% | 7,070 | 15 | City |
| Vista | 7 | 99,444 | 98,833 | 0.12% | 5,242 | 19 | City |
| San Marcos | 8 | 97,040 | 94,938 | 0.43% | 3,949 | 25 | City |
| Encinitas | 9 | 60,921 | 61,999 | -0.35% | 3,197 | 19 | City |
| La Mesa | 10 | 60,685 | 61,094 | -0.13% | 6,675 | 9 | City |
| Santee | 11 | 58,915 | 59,859 | -0.32% | 3,563 | 17 | City |
| National City | 12 | 57,706 | 61,476 | -1.29% | 7,858 | 7 | City |
| Poway | 13 | 49,597 | 48,785 | 0.33% | 1,269 | 39 | City |
| Lemon Grove | 14 | 27,895 | 27,752 | 0.1% | 7,191 | 4 | City |
| Imperial Beach | 15 | 25,434 | 26,101 | -0.52% | 5,926 | 4 | City |
| Coronado | 16 | 17,493 | 20,180 | -2.98% | 2,158 | 8 | City |
| Solana Beach | 17 | 12,853 | 12,925 | -0.12% | 3,765 | 3 | City |
| Del Mar | 18 | 3,891 | 3,945 | -0.28% | 2,266 | 2 | City |
San Diego is the largest city in San Diego County, with a population of 1,409,359.
Del Mar is the smallest city in San Diego County, with a population of 3,891.
There are 18 cities in San Diego County, California.