Cheap flights from St. Louis to London from £239

In general, October is the cheapest month to fly from St. Louis to London Heathrow Airport. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around £492. The month of November is another great option to travel to London Heathrow Airport, with average flight prices from St. Louis averaging around £528.

On average, the least expensive day to fly to London Heathrow Airport from St. Louis is on a Friday. momondo users have found tickets for Friday departures for as low as £476. However, this price may fluctuate depending on the airline, the season, and holidays. Be sure to avoid booking your departure on a Tuesday as prices are generally higher than usual. According to our data, the average ticket price to London Heathrow Airport on Tuesday is £905.

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

You are more likely to see cheaper flights to London Heathrow Airport from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to London Heathrow Airport for around £646 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London Heathrow Airport from St. Louis for as low as £527 on momondo.

There is only 1 cabin class available to choose from on St. Louis to London Heathrow Airport flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

As of May 2026, prices for St. Louis to London Heathrow Airport flights are approximately 5% more expensive when compared to flights at the same time last year.

Atlanta (ATL) was the most common stop: 86% of momondo users choosing one-stop flights on this route connected there.

Flights via Dallas (DFW) offer the lowest average return price of £527.

Flights connecting via Atlanta (ATL) have the shortest average one-way travel time: 10h 28m.

Atlanta (ATL) has the shortest average stopover time for this route: 1h 31m.

As of May 2026, there are 2 flights per day flying from St. Louis to London Heathrow Airport. The most common time of day flights depart is 21:00, with 100% of flights taking off in the evening.

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