| | Tiffin, OH | Warren, MI | United States |
| Population | 17,882 | 138,996 | 329,725,481 |
| Female Population | 51.1% | 51.1% | 50.5% |
| Male Population | 48.9% | 48.9% | 49.5% |
| Median Age | 35.5 | 39.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 17,876 | 134,083 | 309,327,143 |
| Population - 2000 | 18,135 | 138,247 | 285,036,114 |
| Population - 1990 | 18,604 | 144,864 | 251,960,433 |
| Pop. 2000 to Now | -4.3% | -3.9% | 15.6% |
| Pop. 1990 to Now | -6.7% | -8.3% | 30.8% |
| space4 | | | |
| Population Density | 2,603.7 | 4,045.3 | 93.4 |
| Land Area | 6.9 | 34.4 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Tiffin, OH | Warren, MI | United States |
| Age 0 to 4 | 4.3% | 5.9% | 5.9% |
| Age 5 to 9 | 5.2% | 5.9% | 6.1% |
| Age 10 to 14 | 5.8% | 5.9% | 6.6% |
| Age 15 to 17 | 3.4% | 3.7% | 3.9% |
| Age 18 to 20 | 11.8% | 3.2% | 4.0% |
| Age 21 to 24 | 6.6% | 4.8% | 5.2% |
| Age 25 to 34 | 12.3% | 15.4% | 13.8% |
| Age 35 to 44 | 10.2% | 12.5% | 12.9% |
| Age 45 to 54 | 11.6% | 12.8% | 12.6% |
| Age 55 to 59 | 5.1% | 7.2% | 6.7% |
| Age 60 to 64 | 5.8% | 6.7% | 6.3% |
| Age 65 to 74 | 8.7% | 8.9% | 9.6% |
| Age 75 to 84 | 5.9% | 4.6% | 4.5% |
| Age 85 and over | 3.5% | 2.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Tiffin, OH | Warren, MI | United States |
| White | 88.9% | 62.6% | 59.4% |
| Black | 4.2% | 20.7% | 12.2% |
| Asian | 1.1% | 10.5% | 5.6% |
| Native American | 0.3% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.2% | 0.4% |
| Two or More Races | 1.8% | 3.3% | 3.2% |
| Hispanic | 3.6% | 2.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Tiffin, OH | Warren, MI | United States |
| Married Population | 38.6% | 43.7% | 49.8% |
| Currently Married | 36.8% | 41.8% | 48.0% |
| Married but Separated | 1.8% | 1.8% | 1.8% |
| Single Population | 61.4% | 56.3% | 50.2% |
| Never Married | 42.0% | 37.8% | 33.8% |
| Divorced | 12.4% | 11.8% | 10.8% |
| Widowed | 7.0% | 6.7% | 5.6% |
| space5 | | | |
| Household Size | 2.17 | 2.53 | 2.60 |
| Households | 7,193 | 54,502 | 124,010,992 |
| Family Households | 3,834 | 33,896 | 80,755,759 |
| Married couple, w/children | 23.1% | 26.0% | 30.5% |
| Married couple, no children | 46.6% | 38.5% | 42.9% |
| Non Family Households | 3,359 | 20,606 | 43,255,233 |
| Single householder, w/children | 22.3% | 17.9% | 15.8% |
| Single householder, no children | 8.0% | 17.6% | 10.8% |