| | Greenville, OH | Celina, OH | United States |
| Population | 12,785 | 10,890 | 329,725,481 |
| Female Population | 54.2% | 50.0% | 50.5% |
| Male Population | 45.8% | 50.0% | 49.5% |
| Median Age | 45.7 | 38.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 13,251 | 10,420 | 309,327,143 |
| Population - 2000 | 13,294 | 10,303 | 285,036,114 |
| Population - 1990 | 12,863 | 9,650 | 251,960,433 |
| Pop. 2000 to Now | -5.0% | 1.3% | 15.6% |
| Pop. 1990 to Now | -1.8% | 8.2% | 30.8% |
| space4 | | | |
| Population Density | 1,926.6 | 2,185.9 | 93.4 |
| Land Area | 6.6 | 5.0 | 3,531,905.4 |
| Water Area | 0.1 | 0.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Greenville, OH | Celina, OH | United States |
| Age 0 to 4 | 4.3% | 6.7% | 5.9% |
| Age 5 to 9 | 7.4% | 6.0% | 6.1% |
| Age 10 to 14 | 6.3% | 8.1% | 6.6% |
| Age 15 to 17 | 3.6% | 2.3% | 3.9% |
| Age 18 to 20 | 3.5% | 5.1% | 4.0% |
| Age 21 to 24 | 4.2% | 5.2% | 5.2% |
| Age 25 to 34 | 9.5% | 12.5% | 13.8% |
| Age 35 to 44 | 10.4% | 11.2% | 12.9% |
| Age 45 to 54 | 10.1% | 11.1% | 12.6% |
| Age 55 to 59 | 7.5% | 8.0% | 6.7% |
| Age 60 to 64 | 8.7% | 6.3% | 6.3% |
| Age 65 to 74 | 10.6% | 10.9% | 9.6% |
| Age 75 to 84 | 9.0% | 4.9% | 4.5% |
| Age 85 and over | 5.1% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Greenville, OH | Celina, OH | United States |
| White | 94.8% | 89.0% | 59.4% |
| Black | 1.3% | 2.1% | 12.2% |
| Asian | 0.0% | 0.3% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 3.2% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 1.9% | 2.4% | 3.2% |
| Hispanic | 1.6% | 3.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Greenville, OH | Celina, OH | United States |
| Married Population | 44.8% | 50.9% | 49.8% |
| Currently Married | 44.0% | 48.6% | 48.0% |
| Married but Separated | 0.8% | 2.3% | 1.8% |
| Single Population | 55.2% | 49.1% | 50.2% |
| Never Married | 22.5% | 31.9% | 33.8% |
| Divorced | 18.1% | 11.8% | 10.8% |
| Widowed | 14.5% | 5.4% | 5.6% |
| space5 | | | |
| Household Size | 2.10 | 2.40 | 2.60 |
| Households | 5,958 | 4,488 | 124,010,992 |
| Family Households | 3,016 | 2,694 | 80,755,759 |
| Married couple, w/children | 26.4% | 27.0% | 30.5% |
| Married couple, no children | 46.5% | 48.5% | 42.9% |
| Non Family Households | 2,942 | 1,794 | 43,255,233 |
| Single householder, w/children | 17.6% | 17.0% | 15.8% |
| Single householder, no children | 9.4% | 7.4% | 10.8% |