| | Belleair, FL | Seminole, FL | United States |
| Population | 4,266 | 19,224 | 329,725,481 |
| Female Population | 52.5% | 52.3% | 50.5% |
| Male Population | 47.5% | 47.7% | 49.5% |
| Median Age | 55.9 | 53.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,945 | 17,322 | 309,327,143 |
| Population - 2000 | 4,067 | 10,890 | 285,036,114 |
| Population - 1990 | 3,968 | 9,251 | 251,960,433 |
| Pop. 2000 to Now | 5.8% | 73.2% | 15.6% |
| Pop. 1990 to Now | 8.4% | 103.9% | 30.8% |
| space4 | | | |
| Population Density | 2,464.5 | 3,728.5 | 93.4 |
| Land Area | 1.7 | 5.2 | 3,531,905.4 |
| Water Area | 0.8 | 0.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Belleair, FL | Seminole, FL | United States |
| Age 0 to 4 | 5.9% | 3.3% | 5.9% |
| Age 5 to 9 | 1.9% | 4.5% | 6.1% |
| Age 10 to 14 | 3.2% | 4.4% | 6.6% |
| Age 15 to 17 | 2.0% | 1.9% | 3.9% |
| Age 18 to 20 | 0.6% | 2.8% | 4.0% |
| Age 21 to 24 | 2.7% | 3.6% | 5.2% |
| Age 25 to 34 | 15.0% | 7.8% | 13.8% |
| Age 35 to 44 | 6.5% | 10.3% | 12.9% |
| Age 45 to 54 | 9.8% | 13.0% | 12.6% |
| Age 55 to 59 | 7.5% | 7.9% | 6.7% |
| Age 60 to 64 | 8.7% | 9.0% | 6.3% |
| Age 65 to 74 | 21.4% | 15.3% | 9.6% |
| Age 75 to 84 | 12.0% | 11.5% | 4.5% |
| Age 85 and over | 2.7% | 4.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Belleair, FL | Seminole, FL | United States |
| White | 85.2% | 82.2% | 59.4% |
| Black | 0.7% | 3.0% | 12.2% |
| Asian | 3.5% | 4.5% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 2.7% | 1.3% | 3.2% |
| Hispanic | 7.9% | 8.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Belleair, FL | Seminole, FL | United States |
| Married Population | 65.8% | 50.1% | 49.8% |
| Currently Married | 65.8% | 49.6% | 48.0% |
| Married but Separated | 0.0% | 0.5% | 1.8% |
| Single Population | 34.2% | 49.9% | 50.2% |
| Never Married | 17.0% | 23.8% | 33.8% |
| Divorced | 10.9% | 15.5% | 10.8% |
| Widowed | 6.3% | 10.6% | 5.6% |
| space5 | | | |
| Household Size | 2.19 | 2.12 | 2.60 |
| Households | 1,910 | 8,847 | 124,010,992 |
| Family Households | 1,304 | 5,044 | 80,755,759 |
| Married couple, w/children | 23.5% | 18.9% | 30.5% |
| Married couple, no children | 66.3% | 59.7% | 42.9% |
| Non Family Households | 606 | 3,803 | 43,255,233 |
| Single householder, w/children | 2.3% | 11.3% | 15.8% |
| Single householder, no children | 8.0% | 10.2% | 10.8% |