Cheap flights from St. Louis to London from $338

The cheapest month to fly to London from St. Louis is in March. Flight prices, which tend to average around $796, are often lower during this time because this is during the off-season. The month of April is another great option to travel to London, with average flight prices from St. Louis averaging around $813.

The cheapest day to depart from St. Louis to London is on a Thursday. Travelers who choose to depart for London on a Thursday will often find tickets for as low as $805. If your travel schedule is flexible, try to avoid departing on a Friday because tickets tend to average around $1,227. These prices are subject to change though, so be sure to set up a Price Alert for flights to London.

Fly from Lambert-St Louis to London Heathrow for the best Lambert-St Louis - London flight prices

You are more likely to see cheaper flights to London from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to London for around $1,029 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London from St. Louis for as low as $896 on momondo.

There are 3 cabin classes available to choose from on St. Louis to London flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

You could potentially save up to 1% on your flight if you consider stops on a St. Louis to London flight.

British Airways, United Airlines, and Delta are the most popular carriers operating from Lambert-St Louis to London

British Airways, American Airlines and United Airlines are the top three most popular airlines that fly to London from St. Louis according to our data. British Airways is the first choice among our users, with 58% of people opting to fly with this airline when traveling to London. Keep in mind that there are 8 different airlines that fly to London on a routine basis, so you have a few additional options to choose from.

Historically, on average around 18% of flights between St. Louis and London have experienced a delay on any given week. The average delay length over the past 12 months has been 114 minutes.

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

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

According to our data, British Airways have had the least number of delays on this route over the last 12 months; with about 18% of their flights experiencing any sort of delay.

Atlanta (ATL) was the most common stop: 33% of momondo users choosing 1-stop flights on this route connected there.

Flights via Detroit (DTW) offer the lowest average round-trip price of $947.

Flights connecting via Toronto (YYZ) have the shortest average one-way travel time: 10h 20m.

Atlanta (ATL) has the shortest average layover time for this route: 1h 22m.

2 flights are operational daily from St. Louis to London as of October 2026. The most popular departure time for this route is 9:00PM, with 100% of flights per day taking off in the evening.

The number of flights available between St. Louis and London is 15 per week as of October 2026. The most frequent departure day is Tue, with 33% of weekly flights leaving on this day.