| City : | Fairfield City |
| County : | Butler County |
| State : | Ohio (OH) |
| Land Area : | 20.94 sq mi |
| Water Area : | 0.12 sq mi |
| Latitude : | 39.3314204 |
| Longitude : | -84.5427156 |
| Population (2010): | 42,510 |
| Population Estimate (2012) : | 42,638 |
| Population Density : | 2,030.19/sq mi |
| Housing Units (2012) : | 18,803 |
| Median Household Income (2012) : | $54,610 (Ohio : $48,246, USA : $53,046) |
| Median Family Income (2012) : | $65,461 (Ohio : $61,163, USA : $64,585) |
| Median House Price (2012) : | $148,500 (Ohio : $133,700, USA : $181,400) |