| | Winchester, CA | Pasadena, CA | United States |
| Population | 3,300 | 138,771 | 329,725,481 |
| Female Population | 43.3% | 51.2% | 50.5% |
| Male Population | 56.7% | 48.8% | 49.5% |
| Median Age | 38 | 39.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,844 | 137,540 | 309,327,143 |
| Population - 2000 | 2,155 | 133,936 | 285,036,114 |
| Population - 1990 | 1,689 | 131,591 | 251,960,433 |
| Pop. 2000 to Now | 34.1% | 5.3% | 15.6% |
| Pop. 1990 to Now | 71.1% | 7.2% | 30.8% |
| space4 | | | |
| Population Density | 412.1 | 6,044.3 | 93.4 |
| Land Area | 8.0 | 23.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Winchester, CA | Pasadena, CA | United States |
| Age 0 to 4 | 4.8% | 6.0% | 5.9% |
| Age 5 to 9 | 6.1% | 4.3% | 6.1% |
| Age 10 to 14 | 3.5% | 4.8% | 6.6% |
| Age 15 to 17 | 6.0% | 2.8% | 3.9% |
| Age 18 to 20 | 5.5% | 3.0% | 4.0% |
| Age 21 to 24 | 7.9% | 4.4% | 5.2% |
| Age 25 to 34 | 12.2% | 18.2% | 13.8% |
| Age 35 to 44 | 7.8% | 15.4% | 12.9% |
| Age 45 to 54 | 10.6% | 13.6% | 12.6% |
| Age 55 to 59 | 8.8% | 5.9% | 6.7% |
| Age 60 to 64 | 10.8% | 5.4% | 6.3% |
| Age 65 to 74 | 5.5% | 8.7% | 9.6% |
| Age 75 to 84 | 9.8% | 4.8% | 4.5% |
| Age 85 and over | 0.7% | 2.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Winchester, CA | Pasadena, CA | United States |
| White | 35.8% | 33.8% | 59.4% |
| Black | 0.4% | 7.5% | 12.2% |
| Asian | 6.3% | 17.6% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.7% | 0.4% | 0.4% |
| Two or More Races | 1.9% | 4.3% | 3.2% |
| Hispanic | 55.0% | 36.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Winchester, CA | Pasadena, CA | United States |
| Married Population | 42.1% | 45.4% | 49.8% |
| Currently Married | 41.0% | 43.8% | 48.0% |
| Married but Separated | 1.0% | 1.5% | 1.8% |
| Single Population | 57.9% | 54.7% | 50.2% |
| Never Married | 40.3% | 40.4% | 33.8% |
| Divorced | 11.8% | 9.0% | 10.8% |
| Widowed | 5.8% | 5.2% | 5.6% |
| space5 | | | |
| Household Size | 4.08 | 2.45 | 2.60 |
| Households | 809 | 55,191 | 124,010,992 |
| Family Households | 636 | 30,939 | 80,755,759 |
| Married couple, w/children | 30.0% | 29.6% | 30.5% |
| Married couple, no children | 41.0% | 43.4% | 42.9% |
| Non Family Households | 173 | 24,252 | 43,255,233 |
| Single householder, w/children | 14.6% | 12.2% | 15.8% |
| Single householder, no children | 14.3% | 14.8% | 10.8% |