Cheap flights from St. Louis to Denver from $37

The cheapest month to fly to Denver from St. Louis is in January. Flight prices, which tend to average around $214, are often lower during this time because this is during the off-season. If you don’t want to visit Denver in January, then you should wait until February to fly from St. Louis, when ticket prices are also cheap, with an average price of $240.

The cheapest day to depart on your flight to Denver is on a Saturday when prices can be found for as low as $355. This is often the case because there is less demand to fly during this day of the week. The most expensive day to fly to Denver is Sunday, with ticket prices averaging around $493.

The cheapest time of day to fly to Denver is in the evening when flights can be purchased for as low as $253. Flights in the morning are often more expensive with an average ticket price of $460.

Fly from Lambert-St Louis to Denver Intl for the best Lambert-St Louis - Denver Intl flight prices

You are more likely to see cheaper flights to Denver from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Denver for around $281 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Denver from St. Louis for as low as $242 on momondo.

There are 4 cabin classes available to choose from on St. Louis to Denver flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

United Airlines, Delta, and Southwest are the most popular carriers operating from Lambert-St Louis to Denver Intl

Frontier, United Airlines and Southwest are the top three most popular airlines that fly to Denver from St. Louis according to our data. Frontier is the first choice among our users, with 42% of people opting to fly with this airline when traveling to Denver. Keep in mind that there are 4 different airlines that fly to Denver on a routine basis, so you have a few additional options to choose from.

As of November 2026, there are 10 flights per day flying from St. Louis to Denver. The most common time of day flights depart is 8:00AM, with 49% of flights taking off in the afternoon.

73 flights are operational weekly from St. Louis to Denver as of November 2026. The most popular departure day for this route is Fri, with 19% of flights per week taking off on this day.