Frontenac is a city in St. Louis County, Missouri, United States.

Benjamin and Lora Wood, who laid out the community's core called Frontenac Estates, that consisted of 26 two-acre estates, had made frequent trips to Quebec.

[5][6] According to the United States Census Bureau, the city has a total area of 2.88 square miles (7.46 km2), all land.

There were 1,357 housing units at an average density of 471.2 per square mile (181.9/km2).

16.1% of all households were made up of individuals, and 8.6% had someone living alone who was 65 years of age or older.