
Duncan
- County:
- Stephens County
- County Seat:
- Yes
- Area (mi²):
- 42.94
- State:
- Oklahoma
Duncan is a city located in Stephens County, Oklahoma. Duncan has a 2025 population of 23,515. It is also the county seat of .Duncan is currently growing at a rate of 0.74% annually and its population has increased by 3.81% since the most recent census, which recorded a population of 22,652 in 2020.
The average household income in Duncan is $80,585 with a poverty rate of 20.42%. The median age in Duncan is 40 years: 38.2 years for males, and 41.9 years for females.