Hardin
- County:
- Big Horn County
- County Seat:
- Yes
- Area (mi²):
- 2.973
- State:
- Montana
Hardin is a city located in Big Horn County, Montana. Hardin has a 2026 population of 3,719. It is also the county seat of Big Horn County. Hardin is currently declining at a rate of -0.29% annually and its population has decreased by -2.29% since the most recent census, which recorded a population of 3,806 in 2020.