
Frontenac
- County:
- St. Louis County
- County Seat:
- No
- Area (mi²):
- 2.881
- State:
- Missouri
Frontenac is a city located in St. Louis County, Missouri. Frontenac has a 2025 population of 3,795. Frontenac is currently growing at a rate of 0.9% annually and its population has increased by 4.72% since the most recent census, which recorded a population of 3,624 in 2020.
The average household income in Frontenac is $393,584 with a poverty rate of 2.04%. The median age in Frontenac is 45.8 years: 44.7 years for males, and 47.6 years for females.