| | Waipahu, HI | Milpitas, CA | United States |
| Population | 39,927 | 79,593 | 329,725,481 |
| Female Population | 51.5% | 47.1% | 50.5% |
| Male Population | 48.5% | 53.0% | 49.5% |
| Median Age | 38.3 | 35.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 40,221 | 66,694 | 309,327,143 |
| Population - 2000 | 33,108 | 62,698 | 285,036,114 |
| Population - 1990 | 31,435 | 50,686 | 251,960,433 |
| Pop. 2000 to Now | 22.5% | 21.0% | 15.6% |
| Pop. 1990 to Now | 29.0% | 49.7% | 30.8% |
| space4 | | | |
| Population Density | 15,066.8 | 5,829.7 | 93.4 |
| Land Area | 2.7 | 13.7 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Waipahu, HI | Milpitas, CA | United States |
| Age 0 to 4 | 7.0% | 6.6% | 5.9% |
| Age 5 to 9 | 5.6% | 6.1% | 6.1% |
| Age 10 to 14 | 5.5% | 5.8% | 6.6% |
| Age 15 to 17 | 3.6% | 3.4% | 3.9% |
| Age 18 to 20 | 3.1% | 2.6% | 4.0% |
| Age 21 to 24 | 5.7% | 3.9% | 5.2% |
| Age 25 to 34 | 15.8% | 19.8% | 13.8% |
| Age 35 to 44 | 11.6% | 15.5% | 12.9% |
| Age 45 to 54 | 12.1% | 12.2% | 12.6% |
| Age 55 to 59 | 5.6% | 6.1% | 6.7% |
| Age 60 to 64 | 4.8% | 6.0% | 6.3% |
| Age 65 to 74 | 8.6% | 7.2% | 9.6% |
| Age 75 to 84 | 6.8% | 3.3% | 4.5% |
| Age 85 and over | 4.2% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Waipahu, HI | Milpitas, CA | United States |
| White | 3.5% | 10.6% | 59.4% |
| Black | 0.5% | 3.2% | 12.2% |
| Asian | 66.6% | 67.1% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 12.6% | 0.2% | 0.2% |
| Other | 0.1% | 0.1% | 0.4% |
| Two or More Races | 10.3% | 4.7% | 3.2% |
| Hispanic | 6.5% | 13.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Waipahu, HI | Milpitas, CA | United States |
| Married Population | 47.8% | 57.7% | 49.8% |
| Currently Married | 46.3% | 56.0% | 48.0% |
| Married but Separated | 1.5% | 1.7% | 1.8% |
| Single Population | 52.2% | 42.3% | 50.2% |
| Never Married | 36.0% | 31.3% | 33.8% |
| Divorced | 6.6% | 6.4% | 10.8% |
| Widowed | 9.5% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 4.47 | 3.26 | 2.60 |
| Households | 8,651 | 23,681 | 124,010,992 |
| Family Households | 6,900 | 18,878 | 80,755,759 |
| Married couple, w/children | 35.4% | 40.5% | 30.5% |
| Married couple, no children | 30.6% | 39.4% | 42.9% |
| Non Family Households | 1,751 | 4,803 | 43,255,233 |
| Single householder, w/children | 18.4% | 8.7% | 15.8% |
| Single householder, no children | 15.6% | 11.5% | 10.8% |