Cheap flights from London Heathrow Airport to Chicago from £357

The cheapest month to fly to Chicago from London Heathrow Airport is in September. Flight prices, which tend to average around £448, are often lower during this time because this is during the off-season. If you aren’t able to travel during the month of September, then book flights to Chicago from London Heathrow Airport during February instead. Flights to Chicago in February, while not as cheap as those in September, still average around £464.

The cheapest day to depart on your flight to Chicago is on a Wednesday when prices can be found for as low as £644. 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 Chicago is Sunday, with ticket prices averaging around £675.

Flying to Chicago from London Heathrow Airport at midday is the least expensive time of day to depart. momondo users have found prices as low as £647 when looking at flights departing at midday. Flights in the afternoon are often more expensive, with an average ticket price of £671.

Fly from London Heathrow to Chicago O'Hare Intl for the best London Heathrow - Chicago flight prices

You are more likely to see cheaper flights to Chicago from London Heathrow Airport when booking weeks ahead of your departure date. In general, you can expect to find flights to Chicago for around £561 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Chicago from London Heathrow Airport for as low as £469 on momondo.

There are 4 cabin classes available to choose from on London Heathrow to Chicago 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 6% on your flight if you consider stops on a London Heathrow Airport to Chicago flight.

As of March 2026, prices for London Heathrow Airport to Chicago flights are approximately 9% more expensive when compared to flights at the same time last year.

United Airlines, British Airways, and Delta are the most popular carriers operating from London Heathrow to Chicago

British Airways, Lufthansa and United Airlines are the top three most popular airlines that fly to Chicago from London Heathrow Airport according to our data. British Airways is the first choice among our users, with 65% of people opting to fly with this airline when travelling to Chicago. Keep in mind that there are 15 different airlines that fly to Chicago on a routine basis, so you have a few additional options to choose from.

Historically, on average around 10% of flights between London and Chicago have experienced a delay on any given week. The average delay length over the past 12 months has been 169 minutes.

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

Thursday is statistically the day of the week that experiences the fewest delays on this flight route. Friday has historically seen more delays on average compared to the rest of the week.

According to our data, United Airlines have had the fewest delays on this route over the last 12 months, with about 5% of their flights experiencing any sort of delay.

Reykjavik (KEF) was the most common stop: 42% of momondo users choosing one-stop flights on this route connected there.

Flights via Reykjavik (KEF) offer the lowest average return price of £414.

Flights connecting via Dublin (DUB) have the shortest average one-way travel time: 11h 34m.

Frankfurt am Main (FRA) has the shortest average stopover time for this route: 1h 15m.

The number of flights available between London Heathrow Airport and Chicago is 36 per day as of March 2026. The most frequent departure time is 12:00, with 64% of daily flights leaving in the afternoon.

The number of flights available between London Heathrow Airport and Chicago is 257 per week as of March 2026. The most frequent departure day is Sat, with 17% of weekly flights leaving on this day.