| | Seal Beach, CA | Hermosa Beach, CA | United States |
| Population | 25,216 | 19,787 | 329,725,481 |
| Female Population | 55.2% | 45.5% | 50.5% |
| Male Population | 44.8% | 54.5% | 49.5% |
| Median Age | 59.3 | 40.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 24,176 | 19,507 | 309,327,143 |
| Population - 2000 | 24,157 | 18,566 | 285,036,114 |
| Population - 1990 | 25,098 | 18,219 | 251,960,433 |
| Pop. 2000 to Now | -1.1% | 1.3% | 15.6% |
| Pop. 1990 to Now | -4.8% | 3.2% | 30.8% |
| space4 | | | |
| Population Density | 2,235.9 | 13,875.9 | 93.4 |
| Land Area | 11.3 | 1.4 | 3,531,905.4 |
| Water Area | 1.7 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Seal Beach, CA | Hermosa Beach, CA | United States |
| Age 0 to 4 | 3.0% | 5.7% | 5.9% |
| Age 5 to 9 | 3.5% | 5.9% | 6.1% |
| Age 10 to 14 | 4.0% | 4.1% | 6.6% |
| Age 15 to 17 | 2.8% | 2.7% | 3.9% |
| Age 18 to 20 | 1.8% | 0.7% | 4.0% |
| Age 21 to 24 | 1.7% | 2.2% | 5.2% |
| Age 25 to 34 | 7.9% | 22.3% | 13.8% |
| Age 35 to 44 | 8.7% | 13.6% | 12.9% |
| Age 45 to 54 | 10.5% | 16.5% | 12.6% |
| Age 55 to 59 | 7.2% | 7.2% | 6.7% |
| Age 60 to 64 | 7.2% | 5.4% | 6.3% |
| Age 65 to 74 | 19.7% | 9.3% | 9.6% |
| Age 75 to 84 | 14.0% | 3.9% | 4.5% |
| Age 85 and over | 7.9% | 0.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Seal Beach, CA | Hermosa Beach, CA | United States |
| White | 69.9% | 71.8% | 59.4% |
| Black | 2.0% | 0.5% | 12.2% |
| Asian | 12.3% | 7.5% | 5.6% |
| Native American | 0.2% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.3% | 0.0% | 0.2% |
| Other | 0.2% | 0.2% | 0.4% |
| Two or More Races | 3.3% | 7.5% | 3.2% |
| Hispanic | 11.8% | 12.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Seal Beach, CA | Hermosa Beach, CA | United States |
| Married Population | 50.8% | 50.9% | 49.8% |
| Currently Married | 49.1% | 49.8% | 48.0% |
| Married but Separated | 1.7% | 1.1% | 1.8% |
| Single Population | 49.2% | 49.1% | 50.2% |
| Never Married | 23.1% | 38.7% | 33.8% |
| Divorced | 13.5% | 8.1% | 10.8% |
| Widowed | 12.7% | 2.3% | 5.6% |
| space5 | | | |
| Household Size | 1.91 | 2.22 | 2.60 |
| Households | 13,040 | 8,926 | 124,010,992 |
| Family Households | 6,139 | 4,564 | 80,755,759 |
| Married couple, w/children | 22.1% | 30.5% | 30.5% |
| Married couple, no children | 60.4% | 56.4% | 42.9% |
| Non Family Households | 6,901 | 4,362 | 43,255,233 |
| Single householder, w/children | 8.6% | 8.7% | 15.8% |
| Single householder, no children | 9.0% | 4.4% | 10.8% |