Tiffin
- County:
- Seneca County
- County Seat:
- Yes
- Area (mi²):
- 7.38
- State:
- Ohio
Tiffin is a city located in Seneca County, Ohio. Tiffin has a 2026 population of 17,729. It is also the county seat of Seneca County. Tiffin is currently growing at a rate of 0.14% annually but its population has decreased by -1.69% since the most recent census, which recorded a population of 18,034 in 2020.