Cheap flights from Chicago O'Hare Intl Airport to St. Louis from $94

In general, December is the cheapest month to fly from Chicago O'Hare Intl Airport to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $213. The month of September is another great option to travel to St. Louis, with average flight prices from Chicago O'Hare Intl Airport averaging around $217.

The cheapest day to depart on your flight to St. Louis is on a Saturday when prices can be found for as low as $325. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Monday because tickets tend to average around $525. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

Flying to St. Louis from Chicago O'Hare Intl Airport at noon is the least expensive time of day to depart. momondo users have found prices as low as $337 when looking at flights departing at noon. In the evening is when there is more demand to fly to St. Louis, so prices are often more expensive at around $513 per ticket.

Fly from Chicago O'Hare Intl to Lambert-St Louis for the best Chicago O'Hare Intl - Lambert-St Louis flight prices

You are more likely to see cheaper flights to St. Louis from Chicago O'Hare Intl Airport when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $406 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Chicago O'Hare Intl Airport for as low as $171 on momondo.

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

United Airlines and Delta are the most popular carriers operating from Chicago O'Hare Intl to Lambert-St Louis

United Airlines, American Airlines and Contour are the top three most popular airlines that fly to St. Louis from Chicago O'Hare Intl Airport according to our data. United Airlines is the first choice among our users, with 67% of people opting to fly with this airline when traveling to St. Louis. Keep in mind that there are 4 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

Historically, on average around 22% of flights between Chicago and St. Louis have experienced a delay on any given week. The average delay length over the past 12 months has been 127 minutes.

Generally, flights departing in the morning tend to experience fewer delays. Flights at night have, in the past, seen delays more frequently in comparison.

Tuesday is statistically the day of the week which experiences the fewest number of delays on this flight route. Sunday has historically seen more delays on average compared to the rest of the week.

According to our data, United Airlines have had the least number of delays on this route over the last 12 months; with about 21% of their flights experiencing any sort of delay.

As of July 2026, 52 flights take off from Chicago O'Hare Intl Airport and land in St. Louis each day. The most common flight departure time for this route is 11:00PM, with 40% of daily flights taking off in the evening.

367 flights are operational weekly from Chicago O'Hare Intl Airport to St. Louis as of July 2026. The most popular departure day for this route is Fri, with 20% of flights per week taking off on this day.