| | Half Moon Bay, CA | Kailua (Hawaii County), HI | United States |
| Population | 11,792 | 21,460 | 329,725,481 |
| Female Population | 53.3% | 47.4% | 50.5% |
| Male Population | 46.7% | 52.6% | 49.5% |
| Median Age | 44.9 | 42.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,369 | 13,059 | 309,327,143 |
| Population - 2000 | 11,842 | 9,870 | 285,036,114 |
| Population - 1990 | 8,886 | 9,126 | 251,960,433 |
| Pop. 2000 to Now | 5.7% | 48.5% | 15.6% |
| Pop. 1990 to Now | 40.8% | 60.7% | 30.8% |
| space4 | | | |
| Population Density | 1,834.8 | 601.3 | 93.4 |
| Land Area | 6.4 | 35.7 | 3,531,905.4 |
| Water Area | 0.0 | 4.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Half Moon Bay, CA | Kailua (Hawaii County), HI | United States |
| Age 0 to 4 | 5.7% | 6.3% | 5.9% |
| Age 5 to 9 | 5.0% | 5.7% | 6.1% |
| Age 10 to 14 | 4.9% | 6.6% | 6.6% |
| Age 15 to 17 | 3.0% | 2.4% | 3.9% |
| Age 18 to 20 | 6.1% | 2.7% | 4.0% |
| Age 21 to 24 | 5.4% | 4.5% | 5.2% |
| Age 25 to 34 | 9.7% | 13.0% | 13.8% |
| Age 35 to 44 | 10.3% | 12.1% | 12.9% |
| Age 45 to 54 | 14.0% | 13.4% | 12.6% |
| Age 55 to 59 | 8.2% | 7.1% | 6.7% |
| Age 60 to 64 | 7.3% | 7.9% | 6.3% |
| Age 65 to 74 | 12.6% | 12.2% | 9.6% |
| Age 75 to 84 | 5.6% | 4.5% | 4.5% |
| Age 85 and over | 2.2% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Half Moon Bay, CA | Kailua (Hawaii County), HI | United States |
| White | 59.2% | 40.6% | 59.4% |
| Black | 0.1% | 1.2% | 12.2% |
| Asian | 5.3% | 19.3% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 12.0% | 0.2% |
| Other | 0.2% | 0.2% | 0.4% |
| Two or More Races | 3.1% | 14.7% | 3.2% |
| Hispanic | 31.9% | 12.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Half Moon Bay, CA | Kailua (Hawaii County), HI | United States |
| Married Population | 55.5% | 53.5% | 49.8% |
| Currently Married | 54.1% | 52.0% | 48.0% |
| Married but Separated | 1.5% | 1.4% | 1.8% |
| Single Population | 44.5% | 46.5% | 50.2% |
| Never Married | 29.8% | 31.5% | 33.8% |
| Divorced | 9.2% | 10.0% | 10.8% |
| Widowed | 5.6% | 5.0% | 5.6% |
| space5 | | | |
| Household Size | 2.86 | 2.81 | 2.60 |
| Households | 4,117 | 7,506 | 124,010,992 |
| Family Households | 2,832 | 4,873 | 80,755,759 |
| Married couple, w/children | 26.8% | 28.9% | 30.5% |
| Married couple, no children | 53.6% | 49.8% | 42.9% |
| Non Family Households | 1,285 | 2,633 | 43,255,233 |
| Single householder, w/children | 11.8% | 15.6% | 15.8% |
| Single householder, no children | 7.8% | 5.7% | 10.8% |