| | Onyx, CA | Sacramento, CA | United States |
| Population | 661 | 518,605 | 329,725,481 |
| Female Population | 42.5% | 50.8% | 50.5% |
| Male Population | 57.5% | 49.2% | 49.5% |
| Median Age | 55 | 35.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 129 | 467,246 | 309,327,143 |
| Population - 2000 | 476 | 407,018 | 285,036,114 |
| Population - 1990 | 500 | 369,365 | 251,960,433 |
| Pop. 2000 to Now | 34.2% | 26.0% | 15.6% |
| Pop. 1990 to Now | 27.8% | 38.8% | 30.8% |
| space4 | | | |
| Population Density | 57.7 | 5,300.8 | 93.4 |
| Land Area | 11.5 | 97.8 | 3,531,905.4 |
| Water Area | 0.1 | 2.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Onyx, CA | Sacramento, CA | United States |
| Age 0 to 4 | 0.0% | 6.3% | 5.9% |
| Age 5 to 9 | 0.0% | 6.2% | 6.1% |
| Age 10 to 14 | 2.9% | 6.3% | 6.6% |
| Age 15 to 17 | 0.0% | 3.7% | 3.9% |
| Age 18 to 20 | 0.0% | 3.5% | 4.0% |
| Age 21 to 24 | 0.0% | 5.4% | 5.2% |
| Age 25 to 34 | 25.6% | 18.3% | 13.8% |
| Age 35 to 44 | 0.0% | 14.1% | 12.9% |
| Age 45 to 54 | 21.6% | 11.8% | 12.6% |
| Age 55 to 59 | 15.3% | 5.5% | 6.7% |
| Age 60 to 64 | 8.5% | 5.7% | 6.3% |
| Age 65 to 74 | 23.8% | 8.0% | 9.6% |
| Age 75 to 84 | 0.0% | 3.5% | 4.5% |
| Age 85 and over | 2.4% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Onyx, CA | Sacramento, CA | United States |
| White | 90.9% | 31.1% | 59.4% |
| Black | 0.0% | 12.8% | 12.2% |
| Asian | 0.0% | 18.7% | 5.6% |
| Native American | 0.0% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 1.8% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 9.1% | 5.9% | 3.2% |
| Hispanic | 0.0% | 28.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Onyx, CA | Sacramento, CA | United States |
| Married Population | 7.6% | 43.6% | 49.8% |
| Currently Married | 5.1% | 41.1% | 48.0% |
| Married but Separated | 2.5% | 2.6% | 1.8% |
| Single Population | 92.4% | 56.4% | 50.2% |
| Never Married | 39.6% | 40.5% | 33.8% |
| Divorced | 34.4% | 11.2% | 10.8% |
| Widowed | 18.4% | 4.8% | 5.6% |
| space5 | | | |
| Household Size | 2.09 | 2.63 | 2.60 |
| Households | 316 | 194,004 | 124,010,992 |
| Family Households | 128 | 115,399 | 80,755,759 |
| Married couple, w/children | 0.0% | 30.6% | 30.5% |
| Married couple, no children | 13.3% | 34.9% | 42.9% |
| Non Family Households | 188 | 78,605 | 43,255,233 |
| Single householder, w/children | 14.1% | 20.4% | 15.8% |
| Single householder, no children | 72.7% | 14.1% | 10.8% |