| | Los Osos, CA | Folsom, CA | United States |
| Population | 15,692 | 79,201 | 329,725,481 |
| Female Population | 48.7% | 49.1% | 50.5% |
| Male Population | 51.3% | 50.9% | 49.5% |
| Median Age | 47.9 | 40.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 14,924 | 72,133 | 309,327,143 |
| Population - 2000 | 14,540 | 51,884 | 285,036,114 |
| Population - 1990 | 14,716 | 29,802 | 251,960,433 |
| Pop. 2000 to Now | 8.9% | 59.4% | 15.6% |
| Pop. 1990 to Now | 7.6% | 177.6% | 30.8% |
| space4 | | | |
| Population Density | 1,229.5 | 2,848.3 | 93.4 |
| Land Area | 12.8 | 27.8 | 3,531,905.4 |
| Water Area | 0.0 | 2.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Los Osos, CA | Folsom, CA | United States |
| Age 0 to 4 | 6.0% | 5.3% | 5.9% |
| Age 5 to 9 | 5.8% | 6.3% | 6.1% |
| Age 10 to 14 | 3.6% | 7.8% | 6.6% |
| Age 15 to 17 | 2.7% | 4.5% | 3.9% |
| Age 18 to 20 | 2.6% | 2.8% | 4.0% |
| Age 21 to 24 | 4.1% | 4.1% | 5.2% |
| Age 25 to 34 | 10.8% | 11.3% | 13.8% |
| Age 35 to 44 | 12.3% | 15.8% | 12.9% |
| Age 45 to 54 | 10.8% | 17.6% | 12.6% |
| Age 55 to 59 | 6.5% | 6.4% | 6.7% |
| Age 60 to 64 | 9.1% | 5.6% | 6.3% |
| Age 65 to 74 | 15.8% | 7.4% | 9.6% |
| Age 75 to 84 | 7.4% | 3.6% | 4.5% |
| Age 85 and over | 2.6% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Los Osos, CA | Folsom, CA | United States |
| White | 72.4% | 55.9% | 59.4% |
| Black | 0.3% | 4.5% | 12.2% |
| Asian | 4.2% | 17.7% | 5.6% |
| Native American | 0.3% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.3% | 0.2% |
| Other | 0.5% | 0.5% | 0.4% |
| Two or More Races | 2.8% | 5.0% | 3.2% |
| Hispanic | 19.5% | 15.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Los Osos, CA | Folsom, CA | United States |
| Married Population | 55.6% | 57.2% | 49.8% |
| Currently Married | 54.7% | 55.9% | 48.0% |
| Married but Separated | 0.9% | 1.4% | 1.8% |
| Single Population | 44.4% | 42.8% | 50.2% |
| Never Married | 28.5% | 28.1% | 33.8% |
| Divorced | 10.6% | 10.7% | 10.8% |
| Widowed | 5.2% | 3.9% | 5.6% |
| space5 | | | |
| Household Size | 2.50 | 2.70 | 2.60 |
| Households | 6,237 | 27,275 | 124,010,992 |
| Family Households | 4,079 | 19,906 | 80,755,759 |
| Married couple, w/children | 27.7% | 43.7% | 30.5% |
| Married couple, no children | 55.6% | 40.0% | 42.9% |
| Non Family Households | 2,158 | 7,369 | 43,255,233 |
| Single householder, w/children | 7.9% | 8.8% | 15.8% |
| Single householder, no children | 8.8% | 7.5% | 10.8% |