| | Fairfield, OH | Mayfield, OH | United States |
| Population | 44,550 | 3,361 | 329,725,481 |
| Female Population | 52.3% | 51.4% | 50.5% |
| Male Population | 47.7% | 48.6% | 49.5% |
| Median Age | 39.7 | 48 | 38.4 |
| space3 | | | |
| Population - 2010 | 42,556 | 3,474 | 309,327,143 |
| Population - 2000 | 42,097 | 3,435 | 285,036,114 |
| Population - 1990 | 39,729 | 3,462 | 251,960,433 |
| Pop. 2000 to Now | 1.2% | -2.6% | 15.6% |
| Pop. 1990 to Now | 7.2% | -3.3% | 30.8% |
| space4 | | | |
| Population Density | 2,130.6 | 850.2 | 93.4 |
| Land Area | 20.9 | 4.0 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Fairfield, OH | Mayfield, OH | United States |
| Age 0 to 4 | 6.5% | 2.9% | 5.9% |
| Age 5 to 9 | 5.1% | 4.1% | 6.1% |
| Age 10 to 14 | 6.5% | 5.3% | 6.6% |
| Age 15 to 17 | 4.2% | 6.4% | 3.9% |
| Age 18 to 20 | 3.3% | 3.0% | 4.0% |
| Age 21 to 24 | 5.0% | 6.3% | 5.2% |
| Age 25 to 34 | 12.9% | 9.2% | 13.8% |
| Age 35 to 44 | 13.0% | 9.5% | 12.9% |
| Age 45 to 54 | 11.2% | 12.3% | 12.6% |
| Age 55 to 59 | 7.7% | 12.3% | 6.7% |
| Age 60 to 64 | 7.6% | 7.6% | 6.3% |
| Age 65 to 74 | 9.6% | 12.1% | 9.6% |
| Age 75 to 84 | 4.3% | 8.7% | 4.5% |
| Age 85 and over | 2.9% | 0.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Fairfield, OH | Mayfield, OH | United States |
| White | 66.6% | 93.2% | 59.4% |
| Black | 15.7% | 3.0% | 12.2% |
| Asian | 5.6% | 2.1% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 1.2% | 0.0% | 0.4% |
| Two or More Races | 3.8% | 0.4% | 3.2% |
| Hispanic | 7.1% | 1.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Fairfield, OH | Mayfield, OH | United States |
| Married Population | 49.7% | 60.1% | 49.8% |
| Currently Married | 48.7% | 57.6% | 48.0% |
| Married but Separated | 1.1% | 2.5% | 1.8% |
| Single Population | 50.3% | 39.9% | 50.2% |
| Never Married | 29.1% | 31.2% | 33.8% |
| Divorced | 13.7% | 4.6% | 10.8% |
| Widowed | 7.4% | 4.0% | 5.6% |
| space5 | | | |
| Household Size | 2.40 | 2.37 | 2.60 |
| Households | 18,342 | 1,416 | 124,010,992 |
| Family Households | 11,730 | 986 | 80,755,759 |
| Married couple, w/children | 29.9% | 21.4% | 30.5% |
| Married couple, no children | 42.4% | 64.3% | 42.9% |
| Non Family Households | 6,612 | 430 | 43,255,233 |
| Single householder, w/children | 16.6% | 9.0% | 15.8% |
| Single householder, no children | 11.0% | 5.3% | 10.8% |