Cheap flights from London to Chicago from £349

The cheapest month to fly to Chicago from London is in September. Flight prices, which tend to average around £429, 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 during November instead. Flights to Chicago in November, while not as cheap as those in September, still average around £430.

The cheapest day to depart on your flight to Chicago is on a Wednesday when prices can be found for as low as £619. 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 £657.

Flying to Chicago from London at midday is the least expensive time of day to depart. momondo users have found prices as low as £631 when looking at flights departing at midday. Flights in the afternoon are often more expensive, with an average ticket price of £666.

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

You are more likely to see cheaper flights to Chicago from London when booking weeks ahead of your departure date. In general, you can expect to find flights to Chicago for around £546 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 for as low as £512 on momondo.

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

United Airlines, Lufthansa, and Delta are the most popular carriers operating from London to Chicago

British Airways, Lufthansa and Icelandair are the top three most popular airlines that fly to Chicago from London 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 14 different airlines that fly to Chicago on a routine basis, so you have a few additional options to choose from.

Historically, on average around 11% 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 170 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: 41% of momondo users choosing one-stop flights on this route connected there.

Flights via Reykjavik (KEF) offer the lowest average return price of £358.

Flights connecting via Amsterdam (AMS) have the shortest average one-way travel time: 10h 50m.

Reykjavik (KEF) has the shortest average stopover time for this route: 1h 08m.

As of February 2026, 39 flights take off from London and land in Chicago each day. The most common flight departure time for this route is 12:00, with 65% of daily flights taking off in the afternoon.

The number of flights available between London and Chicago is 274 per week as of February 2026. The most frequent departure day is Sat, with 16% of weekly flights leaving on this day.