| | Seffner, FL | Clermont, FL | United States |
| Population | 8,484 | 41,562 | 329,725,481 |
| Female Population | 51.0% | 53.2% | 50.5% |
| Male Population | 49.0% | 46.9% | 49.5% |
| Median Age | 39.3 | 42 | 38.4 |
| space3 | | | |
| Population - 2010 | 7,480 | 28,879 | 309,327,143 |
| Population - 2000 | 5,467 | 9,333 | 285,036,114 |
| Population - 1990 | 5,371 | 6,910 | 251,960,433 |
| Pop. 2000 to Now | 65.4% | 327.0% | 15.6% |
| Pop. 1990 to Now | 68.4% | 476.7% | 30.8% |
| space4 | | | |
| Population Density | 2,352.1 | 2,915.6 | 93.4 |
| Land Area | 3.6 | 14.3 | 3,531,905.4 |
| Water Area | 0.2 | 2.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Seffner, FL | Clermont, FL | United States |
| Age 0 to 4 | 9.7% | 3.6% | 5.9% |
| Age 5 to 9 | 5.6% | 5.8% | 6.1% |
| Age 10 to 14 | 6.5% | 9.2% | 6.6% |
| Age 15 to 17 | 4.8% | 3.0% | 3.9% |
| Age 18 to 20 | 2.5% | 2.5% | 4.0% |
| Age 21 to 24 | 5.6% | 6.2% | 5.2% |
| Age 25 to 34 | 9.9% | 10.1% | 13.8% |
| Age 35 to 44 | 14.3% | 12.3% | 12.9% |
| Age 45 to 54 | 14.1% | 10.9% | 12.6% |
| Age 55 to 59 | 6.5% | 7.2% | 6.7% |
| Age 60 to 64 | 7.4% | 5.4% | 6.3% |
| Age 65 to 74 | 8.8% | 13.9% | 9.6% |
| Age 75 to 84 | 3.4% | 7.3% | 4.5% |
| Age 85 and over | 0.8% | 2.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Seffner, FL | Clermont, FL | United States |
| White | 55.3% | 53.6% | 59.4% |
| Black | 15.3% | 14.0% | 12.2% |
| Asian | 0.4% | 4.3% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.0% | 0.6% | 0.4% |
| Two or More Races | 2.8% | 7.5% | 3.2% |
| Hispanic | 26.1% | 19.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Seffner, FL | Clermont, FL | United States |
| Married Population | 52.1% | 55.0% | 49.8% |
| Currently Married | 50.5% | 54.3% | 48.0% |
| Married but Separated | 1.6% | 0.7% | 1.8% |
| Single Population | 47.9% | 45.0% | 50.2% |
| Never Married | 31.5% | 27.3% | 33.8% |
| Divorced | 12.1% | 9.7% | 10.8% |
| Widowed | 4.4% | 8.0% | 5.6% |
| space5 | | | |
| Household Size | 3.07 | 2.70 | 2.60 |
| Households | 2,746 | 15,349 | 124,010,992 |
| Family Households | 2,122 | 10,790 | 80,755,759 |
| Married couple, w/children | 28.2% | 33.4% | 30.5% |
| Married couple, no children | 47.2% | 45.7% | 42.9% |
| Non Family Households | 624 | 4,559 | 43,255,233 |
| Single householder, w/children | 15.7% | 7.9% | 15.8% |
| Single householder, no children | 8.9% | 13.0% | 10.8% |