| Official Name: | Fairfield Township |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Indiana |
| Subdivision Type2: | County |
| Subdivision Name2: | DeKalb |
| Government Type: | Indiana township |
| Area Total Sq Mi: | 35.98 |
| Area Land Sq Mi: | 35.66 |
| Area Water Sq Mi: | 0.31 |
| Population As Of: | 2020 |
| Population Footnotes: | [1] |
| Population Total: | 1367 |
| Population Density Sq Mi: | 38.4 |
| Elevation Footnotes: | [2] |
| Elevation M: | 292 |
| Elevation Ft: | 958 |
| Coordinates: | 41.4789°N -85.1328°W |
| Blank Name: | FIPS code |
| Blank Info: | 18-22288[3] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 453284 |
Fairfield Township is one of fifteen townships in DeKalb County, Indiana. As of the 2020 census, its population was 1,367, representing a tiny decline from 1,368 at the 2010 census,[4] and it contained 661 housing units.
Fairfield Township was founded in 1844.[5]
The Maria and Franklin Wiltrout Polygonal Barn was added to the National Register of Historic Places in 1993.
According to the 2010 census, the township has a total area of, of which (or 99.11%) is land and (or 0.86%) is water.[4] Indian Lake, Lower Story Lake and Upper Story Lake are in this township.