| | Greenfield, OH | Fostoria, OH | United States |
| Population | 4,197 | 12,785 | 329,725,481 |
| Female Population | 52.9% | 49.3% | 50.5% |
| Male Population | 47.1% | 50.7% | 49.5% |
| Median Age | 38.7 | 35.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 4,643 | 13,421 | 309,327,143 |
| Population - 2000 | 4,906 | 13,931 | 285,036,114 |
| Population - 1990 | 5,172 | 14,983 | 251,960,433 |
| Pop. 2000 to Now | -7.0% | -5.3% | 15.6% |
| Pop. 1990 to Now | -11.8% | -11.9% | 30.8% |
| space4 | | | |
| Population Density | 2,018.8 | 1,695.2 | 93.4 |
| Land Area | 2.1 | 7.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Greenfield, OH | Fostoria, OH | United States |
| Age 0 to 4 | 9.3% | 9.7% | 5.9% |
| Age 5 to 9 | 4.0% | 6.5% | 6.1% |
| Age 10 to 14 | 6.7% | 6.3% | 6.6% |
| Age 15 to 17 | 2.8% | 4.7% | 3.9% |
| Age 18 to 20 | 2.0% | 1.6% | 4.0% |
| Age 21 to 24 | 5.9% | 5.7% | 5.2% |
| Age 25 to 34 | 14.6% | 15.0% | 13.8% |
| Age 35 to 44 | 10.6% | 9.8% | 12.9% |
| Age 45 to 54 | 10.5% | 9.6% | 12.6% |
| Age 55 to 59 | 6.1% | 8.0% | 6.7% |
| Age 60 to 64 | 6.7% | 7.8% | 6.3% |
| Age 65 to 74 | 15.9% | 8.2% | 9.6% |
| Age 75 to 84 | 4.1% | 4.9% | 4.5% |
| Age 85 and over | 0.9% | 2.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Greenfield, OH | Fostoria, OH | United States |
| White | 94.7% | 76.0% | 59.4% |
| Black | 1.4% | 5.0% | 12.2% |
| Asian | 0.0% | 1.5% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 1.3% | 2.7% | 3.2% |
| Hispanic | 2.7% | 14.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Greenfield, OH | Fostoria, OH | United States |
| Married Population | 41.9% | 45.7% | 49.8% |
| Currently Married | 40.3% | 41.7% | 48.0% |
| Married but Separated | 1.6% | 3.9% | 1.8% |
| Single Population | 58.1% | 54.3% | 50.2% |
| Never Married | 27.5% | 32.7% | 33.8% |
| Divorced | 21.5% | 14.2% | 10.8% |
| Widowed | 9.1% | 7.4% | 5.6% |
| space5 | | | |
| Household Size | 2.35 | 2.42 | 2.60 |
| Households | 1,734 | 5,139 | 124,010,992 |
| Family Households | 1,063 | 2,978 | 80,755,759 |
| Married couple, w/children | 16.5% | 29.0% | 30.5% |
| Married couple, no children | 45.8% | 34.5% | 42.9% |
| Non Family Households | 671 | 2,161 | 43,255,233 |
| Single householder, w/children | 30.5% | 27.0% | 15.8% |
| Single householder, no children | 7.2% | 9.5% | 10.8% |